Lowepro continues to make a comprehensive line of camera bags for film-based photography. For several years now I've been using their Mini Trekker backpack-style camera bag ($140; www.lowepro.com), and I think it's terrific. It can hold one or two 35mm SLR bodies, four or five lenses of various focal lengths, a flash, and the other requisite camera gear. In mine, for instance, I carry a Canon A2E, a 90-200mm f/2.8 zoom, two wide-angles, a short telephoto lens, and a large Vivitar flash. A beavertail-style pouch on the back of this pack helps hold a tripod, and an exterior pocket allows me to organize spare film, batteries, cleaning supplies, and so on. It carries comfortably and protects my gear well. Plus, it looks nice and doesn't yell, "Expensive cameras insidesteal me!" like some bags can.
And, if that's too much bag, check out the Micro Trekker ($60), which can hold an SLR body, 80-200mm zoom, a few other lenses, and extras. Its side and front pockets hold extras, and a small tripod can be strapped on. It's a compact and efficient item.
It won't be too long before digital SLRs are affordable, at which time all your new gear will still fit nicely into either the Mini or Micro Trekker. Happy shooting!