To answer more directly, most of my exposure to Mormons was in ElDorado county in NorCal

Mostly really nice people. A little bit clique-ish.
My daughter (Catholic at the time—pretty much agnostic now) went to public school with a lot of Mormons. (Same school district as Ian Book, but about a decade earlier.)

Some of her friends tried to introduce her to it, but the parents never really pushed on us. She even went to a few events.

The Mormons all seemed to do business with one another. For example, if one had a tire store, all the Mormons would go there. I think there was some preferential pricing or treatment that was not explicit, but certainly evident.