This author has previously proposed two senate redistricting plans and analyzed the state democrats' official proposal.  The basic rules that any plan must satisfy are explained in the first article.

Michigan Redistricting: Two Possible State Senate Maps
Michigan Redistricting: Analysis of Democrats State Senate Plan

The Republican plan bears significant resemblance to my first plan.  Many of the differences can be explained by trying to avoid putting two senators in the same district.  The plan manages to avoid putting any non-term-limited senators together, which is no small feat, as I have seen when drawing maps.

Overall, this is a very solid plan.  It should guarantee a Republican majority for the next decade.  It is also a cleaner map (outside Wayne County) than the current map is.  Nonetheless, there are a few aspects of the map I don't care for.

First, I'll describe the districts and then offer analysis of them.  The numbers in parentheses are the old districts that the new ones roughly correspond to.

1. (2) Safe D [N Detroit, Grosse Pointes, Redford] Bert Johnson
   
2. (?) Safe D [central Detroit, Highland Park, Lincoln Park, Southgate, Allen Park] (open?)
   
3. (1) Safe D [Detroit riverfront, Downriver] Coleman Young
   
4. (3) Safe D [West-central Detroit, Dearborn, Melvindale] Morris Hood
   
5. (5) Safe D [W Detroit, Dearborn Heights, Garden City, Inkster] Tupak Hunter (TL)
   
6. (?) Safe D [SW Wayne, Westland, Taylor] Hoon-Yung Hopgood, Glenn Andersen (TL)
   
7. (7) Safe R(+) [Livonia, Canton, Plymouth, Northville, Wayne city] Patrick Colbeck
   
8. (11) Safe R [N/E Macomb] Jack Brandenburg
   
9. (9) Safe D [Warren, Roseville, Eastpointe, Fraser, S Clinton] Steven Bieda
   
10. (10) Safe R(++) [Sterling Heights, Macomb, N Clinton] Tory Rocca
    
11. (14) Safe D [Farmington, Southfield, Oak Park, Madison Heights] Vincent Gregory
    
12. (12) Safe R [NE Oakland, Pontiac, Bloomfield Twp.] Jim Marleau
    
13. (13) Safe R(+) [Troy, Rochester, Royal Oak, Birmingham] John Pappageorge (TL)
    
14. (26) Safe R(++) [SW Genesee, NW Oakland, Waterford] David Robertson
    
15. Safe R [SW Oakland] Mike Kowall
    
16. Safe R [Jackson, Hillsdale, Branch] Bruce Caswell
    
17. Tossup(-) [Monroe, Lenawee] Randy Richardville (TL)
    
18. Safe D [Ann Arbor, Ypsilanti] Rebekah Warren
    
19. Safe R(++) [Calhoun, Barry, Ionia] Mike Nofs
    
20. Tossup(-) [Kalamazoo County] Tonya Schuitmaker (most of current district)
    
21. Safe R [Berrien, Cass, St. Joseph] John Proos
    
22. Safe R [Livingston, W Washtenaw] Joe Hune
    
23. Safe D [Ingham] Gretchen Whitmer (TL)
    
24. Safe R [Eaton, Clinton, Shiawassee, NE Ingham] Rick Jones
    
25. Safe R [St. Clair, Sanilac, Huron] Phil Pavlov
    
26. (new) Safe R(++++) [VanBuren, Allegan, Kentwood] Tonya Schuitmaker (residence)
    
27. Safe D [Flint, central Genesee] John Gleason (TL)
    
28. Safe R [N Kent, Walker] Mark Jansen (TL)
    
29. Tossup [Grand Rapids, SE Kent] Dave Hildenbrand
    
30. Safe R [Ottawa County] Arlan Meekhof
    
31. Lean R(+) [Bay, Tuscola, Lapeer] Mike Green
    
32. Lean D(-) [Saginaw, W Genesee] Roger Khan (TL)
    
33. Safe R [Montcalm, Isabella, Gratiot, Mecosta, Clare] Judy Emmons
    
34. Tossup(-) [Muskegon, Newaygo, Oceana] Geoff Hansen
    
35. Safe R [NC Lower Peninsula] Darwin Booher
    
36. Tossup(-) [NE Lower Peninsula, Midland] John Moolenaar
    
37. Safe R [NW Lower Peninsula, E Upper Peninsula] Howard Walker
    
38. Tossup [Upper Peninsula excluding Mackinac, Chippewa, Luce] Tom Casperson

COMMENTARY:

The Republican map has the minimum possible six counties broken, with a double break in Genesee.  One of my maps also did this, while the other avoided a double break.  The democrats' map had seven breaks plus a double break.

The Detroit districts are pretty messy.  However, this is necessary to maintain five black-majority districts while also limiting city breaks.  This map manages to avoid breaking Wayne.  Detroit is split five ways, which is essential since any all-Detroit district would have too large a black population.  I particularly like that they used my "8 Mile district" (1), stretching from the Grosse Pointes to Redford.

Patrick Colbeck (7) gets safer, trading the southern tier for Livonia.  Republicans have given up on having two senators in Wayne, which is no longer realistic due to changing demographics.  Colbeck would be a strong conservative candidate to replace Thad McCotter when he moves on.

In Macomb, Republicans finally gave in to temptation and split Clinton Township.  With no splits, the map gets very difficult for Republicans, while adding just one split makes it possible to put the most democrat areas of the county in one district (9).

Meanwhile, Tory Rocca (10) loses democrat Roseville and S Clinton, adding Macomb Twp.  This district contains almost all of Leon Drolet's old state house district.  Could the libertarian-conservative Drolet primary the moderate pro-union Rocca?

Jack Brandenberg (8) adds St. Clair Shores, which was in his old state house district.  This district is a little less Republican, but still safe.

District 11 pulls Madison Heights from 13, which drops Bloomfield Twp. and adds Rochester.  With John Pappageorge term-limited, this district could see a primary between establishment conservative Marty Knollenberg and staunch conservative Tom McMillin.  Knollenberg has announced his intention to run for congress against Gary Peters, but with Peters' district all but certain to be carved up, he won't have a district to run in.

District 12 trades Rochester for Bloomfield Twp.  It should still be safe.  District 15 only loses population to Dave Robertson (renumbered 14), whose district is now primarily Oakland-based.  It loses Mt. Morris and Burton, becoming safe.

Bruce Caswell (16) loses St. Jospeh and Lenawee, adding Jackson.  This is identical to the 90's Jackson-based district.  Jackson will likely go a fourth straight term without a home-county senator, but when Caswell is term-limited, it should finally have one again.

Randy Richardville (17) is term-limited, and his district becomes a tossup, losing chunks of Jackson and Washtenaw and adding Lenawee.  Basically everyone drew this district, as there weren't any reasonable alternatives.

Mike Nofs (19) drops most of Jackson and adds Barry and Ionia.  This district is identical to a proposed district in the original Republican plan ten years ago, before it was amended.  If the original district had held, there would never have been a Senator (or Congressman) Mark Schauer.  It would be nice to see Jase Bolger primary the moderate, SEIU-friendly Nofs, but I don't know that there is any chance of that happening.

Kalamazoo County gained enough population that it can become its own district (20).  It loses a small chunk of Van Buren.  This is bad for Republicans for two reasons.  First, senator Tonya Schuitmaker is from Van Buren.  Second, the district would become a tossup.  Tonya would have to choose between moving to Kalamazoo County, which is most of her current district, or running in a new district (26) centered in Allegan County.  While Tonya represented Van Burn and a chunk of Allegan in the state house, folks in Allegan would probably like to have their own senator.  Conservatives would do well with current state rep. Bob Genetski.

Rick Jones (24) keeps only Eaton, and his new district becomes a suburban Lansing district.  He should still be safe.

Dave Hildenbrand (28) loses Kentwood and adds East GR and GR Twp., which were in his old state house seat.  I'm not sure whether this is a partisan improvement.  This seat stays a tossup.  Meanwhile, 28 will be open and stays solidly Republican.  This would be a good seat for Dave Agema, though the majority of his state house seat is in Ottowa.

All the most democrat areas of Genesee get put into one district (27).  The Western tier gets combined with Saginaw (32).  Democrats may finally break their losing streak in Saginaw.  State rep. Ken Horn has a chance here, but I'm rating this seat lean democrat.

Mike Green gets a safer district (31), losing Arenac, Huron, and Sanilac, and adding Lapeer.

Geoff Hansen (34) loses Mason, making this seat a tossup.

John Moolenaar (36) trades Ogemaw and Crawford for Presque Isle.  I don't like this.  This seat was very close in 2002 when the democrat candidate was a state rep. from Alpena.  Presque Isle is the most democrat part of this district.  Losing Ogemaw does move the Sheltrowns (Dave, Joel) out of this district, though.