We used nationally-based credit unions (PenFed, then NASA) for re-fi's. Rates were good, and things went OK, although they hire local appraisers off a list, and you might get a terrible appraiser (happened to us on our second re-fi.)
Overall, the re-fi's went OK, but be aware that in most cases, whoever you use for a re-fi, it will take longer than new purchase. They generally prioritize new buys, because the buyer can lose the house if they take too long, which obviously won't happen to you. It's annoying how it drags on, but not a problem unless you're trying to get cash out by a certain date, for instance.