Just to agree with the other replies. If ever there was a place you don't need a guide, it's the Berner Oberland.
Rick's chapter on the Berner Oberland in his Switzerland book is one of his very best. Other than the over-emphasis on Gimmelwald, that is (it's fine for a few hours, but hardly the life-changing experience he makes it out to be).
I found it a little hard to follow the chapter before I was there, but once I got there, it was crystal-clear. Basically, it's a U-shaped valley. Lauterbrunnen is at the base, along with Stechelberg and the Trümmelbach Falls. Gimmelwald, Mürren, and the Schilthorn are up one side, and Wengen, Kleine Scheidegg, and the Jungfraujoch are up the other side. (These are just a few of the most prominent places; there's more, of course). Within this area are many days of hikes. I stayed in Mürren and so can't speak for restaurants in the other towns, but the ones in Mürren were quite good (the usual high Swiss prices, but the quality of the food was high as well). My one meal in Gimmelwald was not of the same standard.
Interlaken is near, but not in, the Berner Oberland. Unless you want a casino, a choice of large supermarkets (the towns in the B.O. have one small one each), a sex shop, or a "Paksitani" restaurant (that's what the sign said - like Punxsutawney Phil in Groundhog Day), Interlaken can be skipped.