We are considering a very similar move in the next year or so (also East Coast to MI, to be closer to my family- DHs family is on the East Coast).
I'll share a bit of my experience, although the caveat is that my experience is mostly with rural northern MI, which could be much different than what it's like in southern MI/Grand Rapids.
I grew up in MI and moved to the East Coast 12 years ago. The most immediate difference I noticed when I moved here is that people here are much more private/less likely to smile and say hi as they pass you on the street. People in MI are friendly and don't mind small talk (although they often love to gossip too). In general, people on the East Coast seem more open minded. The East Coast also has a more "busy" feel to it- like people are in a rush to go here or do that, and there are an unlimited number of things you can do (museums, classes, sports, etc). In MI, life feels a bit more laid back, slow, less rushed. You will likely get stuck in a "traffic jam" behind farm equipment on the roads in MI, people often drive under the speed limit, etc. So if you like the "go go go" feel of the East Coast, that might be quite an adjustment. My DH especially hates driving in MI- his East Coast road rage tends to flare up. :) In MI, I feel like there is less pressure to keep up with the Joneses- having a nice house, or a fancy car, having your kids enrolled in three activities at a time, etc., does not seem to be as celebrated/expected there as it is on the East Coast.
You might want to think about the long term implications of the move. Will you be ok being away from your family? What about if you have kids? Will your family travel to visit you in MI, or will you have to take trips back to the East Coast to see them? We use most of our vacation time each year to go to MI because my family does not travel. Once we had kids, the "annual pilgrimage" became even more important, because I want my kids to know my family. Unfortunately, this means we don't have the time to take other vacations.
I want to move back to MI to be closer to my family, but I do worry about it because there are a lot of trade-offs (especially in the region where my family lives). There aren't nearly as many job opportunities as there are on the East Coast. Schools are few and far between, so if we want a good school district, we'll be very limited in where we can live. There isn't as much in the way of programs & classes for kids. The selection in grocery stores is much more limited (and often nearly as expensive). You have to drive to get anywhere- not having a car isn't really an option. We are actually considering southern MI/Grand Rapids area as an option to combat some of these, but these are definitely things to consider if you if you will be outside the major metropolitan areas.
On the plus side, I think my kids will spend a lot more time outside. There are some really amazing places to visit in MI, all within a day's drive. I will enjoy not feeling like I have to impress anybody. I can visit my family over a long weekend, instead of trying to pack in a years' worth of missed time with friends and family into one short week. I have been spoiled by the East Coast in many ways, but I imagine the benefits will far outweigh those things I will be missing.
I hope this helps!