I look for economy of design. If I'm in a situation to carry something big on my belt or in a backpack, I'll go with my Leatherman Wave everytime. But when I'm going to be carrying in pocket, then I gravitate towards my Spartan (augmented with the little screwdriver that fits into the corkscrew). I also have an Adventurer which I carried with me daily in for five years when I was living in Europe. I love that big, locking blade. I guess I'd like to have 'em all, but the designs I like best are pretty basic: Compact, Waiter, Tinker, Spartan, Sportsman.
IMHO, the best new model that Victorinox has come up with in awhile is the Rambler. Amazing to think that they could take the Classic and add a cap-lifter/phillips head screwdriver to it and still have it fit on a key chain. Anyway to get to the original question that started this thread, which tools could I do without. Well, I never cared to have a saw or file. I have no use for a magnifying glass. I don't trust the models with a clock or LED light or pen (just don't see how those features could be made as tough as the rest of the knife ... instead, I'll wear a watch, carry a pen and carry my Photon LED). I would never scale a fish with a SAK scaler. The SAK pliers seem rinky-dink to me, again give me my Wave for that. Don't even get me started on the cuticle pusher or orange peeler. No thanks.