I'm glad I'm not the only one with some zoom lenses that work really well. It's been fun reading this thread.
Effectively, I have three cameras that I use only with zoom lenses. Two of the cameras have prime lenses in their bags, but I use the zooms almost 100% of the time. The third uses a really good zoom lens as its only lens. They are:
Pentax Auto 110 with the 20-40mm zoom lens. I spent the leftover money after a year of college to buy this zoom lens as a personal reward for frugal living. Since all lenses on the Auto 110 have an aperture of f2.8, there's no penalty in light gathering to use this zoom lens, and it is just as clear as the prime lenses that I also own.
After my dad died, I inherited his beloved Konica Autoreflex T3n. He loved fast prime lenses, and the camera came to me with three good lenses. However, I'd read about the tremendous computational achievement that was the Vivitar Series 1 70-210mm zoom back in the early Seventies. My dad lusted after that lens when I was a teenager, but he never splashed out on buying one, so I found a really good used one with the Konica AR mount and bought it. I can see why he lusted after this lens... it is amazing. I've had it now for almost four years, and almost every time I take the camera out for a shoot, I put this lens on. It does really excellent macro shots too.
Last, I bought an Olympus iS-3dlx a couple of years ago for impossibly cheap. I'd had a boss 20+ years ago who owned one and bragged about it all the time. I figured that for $10 I could finally check it out and if it turned out to be a dud I wasn't out too much money. Well, he was right. It is amazing. I think half of the rolls of film I've shot this last year have been through this camera. And, yes, the zoom lens is amazing. There's that word again... amazing. You can't screw another lens onto it, but this zoom is so versatile that it doesn't matter. Also, with the external flash and the internal flash up, three different strobe tubes can illuminate vast areas at night.
I have a few other zoom lenses, like on a Lumix digital super-zoom and on several little P&S cameras, but they're merely adequate.
Scott