I'm headed out to Wyoming in about a month and am looking for a reasonably priced (~500-800) telephoto zoom or prime for wildlife and landscapes that's light enough for backpacking. Right now, the 70-200 f/4L, 200mm 2.8L, and Tamron 70-200mm 2.8 are at the top of my list. I like the Canon 70-200 but am worried it'll be too slow without IS, and I can't afford the premium. The 200mm seems nice, but I'm worried about having a focal length "hole" from 100mm to 200mm. And I know little about the Tamron besides that the price is right.
Secondary question: I have the 17-40L (on crop) and I've been relatively unimpressed with it. The lens seems very sharp at close range, but lacks "punch" for landscapes, even when manual focused. I'm probably going to sell it to raise funds, but I'm not sure what to replace it with. Will the 18-55mm kit lens offer close to the same results at landscape apertures (f/8-f/16)? Or should I look at the Tamron 17-50 or something?