Michigan will see several interesting congressional races in 2018, with one open seat. Michigan has 14 congressional seats.
There are several articles that analyze the general political leanings of the districts.
District 1 (Upper Peninsula, Northern Lower Peninsula) Safe Republican.
CD12: 48.1-47.6 CD14: 52-45 CD16: 55-40 McCain: 48.5 Romney: 53.5 Trump 57.9
Following the retirement of Dan Benishek, conservative retired general Jack Bergman defeated moderate state senator Tom Casperson and former senator Jason Allen 39-32-28 in the R primary. He defeated former Michigan democrat chairman Lon Johnson, a liberal who bought a small house in Kalkaska County, in the general. Veteran Matt Morgan is running for the D nomination, but may be disqualified because he messed up his petitions.
District 2 (Ottowa, Muskegon) Safe Republican.
CD12: 61-34 CD14: 64-33 CD16: 63-33 McCain: 50.4 Romney: 56 Trump 55.8
Republican former state rep. Bill Huizinga won a close primary in 2010 to replace Pete Hoekstra, and was easily reelected since then. He has generally voted a fairly conservative line. This remains the most Republican district in Michigan. Robert Davidson and Nick Schiller are running for the D nomination.