Traveling to Ecuador next month so I plan on renting a quality Canon "L" series lens to take with me. I'm considering the 24-105mm or the 28-300mm and was looking for recommendations. I hear the 28-300 will get pretty heavy as I walk around but I thought the extra reach would be nice at some times. I'll be visiting the Galapagos, so I'd like to get close ups of some of the wildlife - namely turtles, lizards, birds, penguins, and boobies. For those of you who know, how big is the 28-300? Cheers.