In Michigan you're allowed 12 plants per patient. You can be a patient and then be a caregiver for up to 5 more. The max plants one person can have is 72. The plants are tied to the person not the dwelling. So if you were married, both you and your wife could both be patients and have 5 patients allowing you 144 plants in the house. The kicker is you are only allowed 2.5oz per patient of dried bud, so anyone growing the max number of plants breaks this part of the law.
We are new to the medical marijuana scene (2008 ) so we don't have a lot of dispensaries yet, but there are a few. Actually dispensaries aren't mentioned in the Michigan Medical Marihuana Act (yeah they spelled with an 'h' instead of a 'j'... fucking pretentious right? It bugs me greatly... anywho). So at best dispensaries are a legal grey area and at worse they are totally illegal. But it hasn't stopped them from popping up, I can think of 10 or so dispensaries off the top of my head. We also have a lot of 'compassion clubs', basically in every city (even my town of 10,000 has a compassion club.)
Michigan is a beautiful state. We have thousands of lakes and beaches. If you like the outdoors you'll probably like Michigan. With the exception of Ann Arbor, most of our major cities suck. Detroit, Flint, Saginaw, etc are all shit holes (I would know I used to live in Detroit... Hands down the dirtiest city in north america. There is just trash every where, it's unreal.) But if you stay out of the major cities Michigan is nice. Our economy is in the shitter right now, because the auto industry was such a huge part of our economy state wide. But it doesn't sound like you will be moving and looking for a job, so if making money isnt an issue, Michigan is cheap as hell to live in now. In Detroit 8 grand will buy you a 2500 sq ft 5BR 2BA house, in the suburbs you can get the same house still pretty cheap, $150,000-$200,000 depending on the city you choose to call home.
This is the last thing I'll say: It's true I was born in Michigan so I may be biased, but I've lived in Michigan, Florida, Cali, and Oklahoma. Michigan is my favorite place hands down. Plus we are so close to Canada, and Canada is awesome.