I'm in agreement with Version1955
Nice little southern MN town. Far enough from the Twin Cities that people aren't so jaded and in always in a hurry, yet close enough that if you need a night out, a play or a concert, the trip is do-able.
He should keep in mind that Minnesotans have a reputation for being on the reserved side. (Truth is, we think you probably have better things to do than getting to know us.) He'll have to be the person making the first effort, but that's all it takes.
If your brother has kids, getting to know people will be easier. And of course, grocery stores in small(er) towns are hubs, so if he's the least bit outgoing, he'll know everyone in no time.
In my heart's desire, I'd live in a town like that.