well crafted music with a lot of minor and major 7 chords.
That's about the best I'd be able to come up with, though it wouldn't mean much to people who don't play music (or don't understand theory).
There aren't any well-known bands I can think of that feel similar to sf59. There are a handful of more indie groups that do sound like sf59k, but most of them probably have been influenced by sf59 anyway--or maybe vice-versa, Daniel Amos, for instance. But I am pretty curious to hear what suggestions some other members might come up with.