I have personal knowledge of 4 of these:
Minneapolis: Considered one of the very best places to live in in America, because of so much culture. Close to Mayo Clinic in Rochester. I considered here (cousin lives there for years), but the cold...damn! it is just too cold...and this coming from someone who was from Chicago. I mean you can be TOO cold. If you can tolerate maybe 4 months of freeeeezing, then this could be your city. It has everything anyone could want, and ends up at the top of all the best places to live in America lists all the time.
Burlington, Vermont: Close-close friend and ex-employee moved there. He is gay. Moved out because it was TOO gay for him even. He wasn't all that impressed with the area at all. Very, very, very liberal thinking. My friend swore when he lived in Manchester (hour away) that nobody in Vermont had any money. He also swears everyone there wears flannel shirt and jeans. Guess he wasn't into the fashions popular there.
Portland, Maine: Many retirees there. My gay friend moved there, too, and did love the seafood/lobster all over Portland at cheap prices. Thought the arts were pretty active there. Liked the area alot. Check out those taxes tho on retirementliving.com and see if you can live with Maine's taxes. It is a beautiful area, tho. Oh, and the area is a wonderful diversity of people (compared to Burlington). My gay friend does prefer diversity and not an all gay world...sorta like I don't want to move to Florida if I am going to be stuck with all old people around me.
Iowa City, Iowa: Know this area because I am living near there now. Cold in winter, yes...but not like Minneapolis or Chicago. Less windy. It is a DRY cold unlike cold, say, in Houston which is a wet cold. For instance, at 32 degrees in Houston, because of the humidity the cold goes right down into your bones. Lots of congestion in your chest there. At 32 degrees in Iowa City or even Chicago, you are running around in a light jacket or sweater and thinking the weather is Fall crisp and wonderful. Big, big difference. Again, get on retirementliving.com and check Iowa's taxes. Depending on where your money is coming from, Iowa can or cannot take a chunk every year. But Iowa City is a hip, cultural, happening place--and, most of all, SAFE. I live about 1-1/2 away from there now, and this area of America--having been the manufacturing/farm area AND manufacturing has gone to Asia and Mexico now--makes this area a VERY cheap/inexpensive one to live in. Costs here are so low that Chicagoans come here to gamble on the boats and party. Drinks that would cost me $7 in Chicago are $2.50 here. My gym membership to a top gym here is $260 a year with a great pool! The Midwest is cheap to live in. You could also consider how close you will be living to the owner of Berkshire Hathaway, too, in Omaha, I guess. Bottom line: check out pricing in Iowa City on Sperling's Best Places (sperling's.com or sperlings.com) and click on the city compare to compare any city with another you are thinking of moving to if price is an issue (it should be).
You might want to use epodunk.com, too, to check out your cities. Lot and lots of useful info there from how many libraries to the nationalities of a certain cities population (i.e., how many Polish, Argentinians, Asians) to how many gays to how many hospitals...well, you get the idea.