Cool, thanks for the info. I am actually going to be renting some lenses from www.lensrentals.com
and was planning on going with the canon 100-400mm lens and now a wider angle lens as well. I do get there are better lenses out there for my other options as well, but I'm really going for compromise with what I have to carry as well.
But in total for the trip, I plan on having the Tamron I bought, the canon 100-400mm, and an as of yet undecided wide angle lens. I will also have the ef-s 18-55 f3.5-5.6 non-IS that came with the camera, but don't plan on bringing it out too often unless I really have to for some reason.
I'm going to start a separate thread regarding a tripod for the 100-400mm lens in an appropriate topic forum.