I'll throw in my .02 and wish you the best of luck, too...
Disclaimer: The following summaries are my own, honest opinions gathered from living in SoFla my entire life (with the exception of several years I lived in SoCali while going to school in the 90's).
Homestead: Up & coming (booming) city (mainly because of affordable housing in recent years) but it's a PITA commute/ drive anywhere in Miami (beach, grove, downtown, etc) as you're at the Southern most part of the county (BFE).
Kendall (West a/k/a West Kendall): Nice area, but IMO it is over populated/ saturated. Takes forever to get out from the couple of main arteries. And, unfortunately, it does have a high crime rate (vandal/ auto theft)...Probably due to the over saturation of apartment complexes. lol
Kendall (East - a/k/a Pinecrest): Very nice, upper (middle) class community that is mostly family oriented. Quick commute to most places in greater Miami-Dade.
Hialeah: Stay away unless you're into traffic congestion, careless drivers, and a flurry of other issues I won't get into. Same advice goes for: Hialeah Gardens, Carol City (a/k/a Miami Gardens), Liberty City, Overtown, Richmond Heights, Perrine, & Goulds.
Miami Lakes: Nicer part of Hialeah, about 10 minutes from Doral.
Doral: Was mostly an industrial warehouse district due to it's convenient location near the MIA (airport). Over the last 10 or so years, it has been developed quiet extensively for residential. It is an easy commute to most places and pretty much in the center of the county. In case you're a light sleeper, keep in mind that airplane traffic is quite frequent 24/7.
Beaches (All in Dade County): Great place to live (day & night - especially Southern end in SoBe)if you work on any of the island, but commuting may not be your best alternative and parking is typically horrible throughout most of the beach cities. It's best to either use taxi, bike, tom & Jerry, or Vespa (public trans. bites). Most places offer valet if you're ok with overpriced parking, an occasional ding or wheel scuff.
Brickell/ Downtown: Many new hi-rise condos with garage parking, resort style living and near great night life entertainment. Great real estate deals to be had currently, too. Parking is almost as bad as the beach when you're not parked at home. See suggestion above under "beaches" for other options.
Coral Gables/ Coconut Grove: Adjacent to one another and great places to live as you have UM there and lots of young college girls inhabiting the area
Traffic is easily manageable at off-peak hours and your near almost everything. Lots of entertainment choices and pretty much the most affluent part of Miami-Dade. As others have said though, watch out which part of Coconut grove you search as it's a beautiful city on the bay, but use to house the projects and still has sections that are low-income as well as high crime areas. Not where you'd want to park your new M.
If you have the choice of moving wherever you want, don't have kids/ family to be concerned with, I'd be looking for a place near the Grove or on Brickell. If your commute is near Doral, you always be on teh opposite side of the rush hour traffic and have plenty of activities (day & night) to choose from just a few minutes away from your door.
As far as your car tag/ registration... I believe the impact fee was done away with or lowered for new residents, but your best bet would be to perhaps have your military broker/ coordinator register the car in Florida or provide the least expensive option for you since you already know you'll be moving here soon after you get your car.
For more info on your auto registration, go to:
http://www.flhsmv.gov/HTML/titlinf.html
