Any tips on jazz guitar trios or quartets?

Well, almost all good jazz guitarists have their own "sound" to a great degree, so it's a little hard to recommend someone who necessarily sounds like Metheny or Benson. That said, however, you should check out the following electric jazz guitar greats, whose "sound" should probably appeal to you:
1. Tal Farlow
2. Barney Kessel
3. Kenny Burrell
4. Wes Montgomery
5. Grant Green
6. Pat Martino
7. Bill Frisell
8. Larry Corell
9. Herb Ellis
10. John Abercrombie

If "laid back" is one of the key qualities you want, then I should have mentioned (don't know how he slipped my mind, since he is one of my two favorites jazz guitarists) is Jim Hall. Hall's work is deceptively complex, but his sound and style is always "easy on the ears". One of Hall's best recordings, although one of his more challenging, is the duet album that he did with Bill Evans titled "Undercurrent". It's been a personal favorite since I first heard it in the mid 1960's.