Wolf Am I
Umm, I don't know about a good-sized discography but O'Brother seems the obvious one for me, they're relatively new, but they have a really similar sound, try Garden Window by them.
I know two bands they apparently listened to a lot during them recording sessions were Isis and Cave In, but, although you can hear the vibe in the tracks, Isis and Cave In are a lot more 'difficult' to listen to.
You could try Oceansize, maybe, again though, they are slightly stranger.
Instrumentally, you could try Russian Circles.
There is a band in the UK who are just getting quite big called Burn The Fleet (named after a Thrice song) who are similar but have a bit more of a metallic edge to the guitars etc.
Moving Mountains, possibly. A little less aggressive.
Also, I don't know how big of a Thrice fan you are, so you might know the record but the Alchemy Index, which they released after, in terms of Air and Fire, are pretty damn good and its a really similar vibe.
Sorry if I haven't been much help! There isn't many similar bands to them!
I appreciate the help, and I'll definitely give these bands a listen. I am quite the Thrice fan, and to be honest, I only really enjoyed Fire out of the Alchemy Index volumes.