We were a trio for almost three years. I was friends with the piano player and the guitar player joined us. We are each of a different generation, in a different stage of life, and we get along great. We have lots of fun at rehearsals, and our families all know and like each other, though we usually only get together around major events like festivals and such. It's just right.
We've recently added a drummer. He comes from a completely different background, even speaks a different language, and we're playing the whole relationship thing by ear. He are I are most in-tune musically, and I'll try to get together with him outside the framework of the band and see if that doesn't help warm things up.
(p.s. He has a boat, and I know he wants to take us all out one day, and if there is enough beer, my guess is that we'll all come back friends.)