Upload & Sell: Off
to answer the OPs question, what other lenses do you have?
Doh! Minor omission!
I use a 5D II, and have 24-70 2.8, 70-200 2.8, Sigma 85 1.4, 100mm 2.8 macro (no need for that), as well as several older minor deities from years ago.
I toyed with the idea of renting the Canon 28-300 just to lug it around for a week to see what it's like, but I know it weighs half a pound more than my 70-200, and really defeats the purpose.
A few years back, I spent a few months in Vietnam, Laos, and Cambodia with just a 30D and a Sigma 17-70. It's a surprisingly good, lightweight lens, but many times I really wanted more than 70mm of reach.
I've lugged the big lenses around Spain for a month, but travelling by car is very different from taking trains and buses and walking a lot more. I tend to travel light in Asia, partly because of the heat factor, and partly because there's a lot more jostling and attention. Security is never an issue, but little curious fingers often are, and the less I have to fidget with, the better. In Asia, I never have more than two lenses.
And the walking business can't be ignored. If you're carrying water, guidebooks, and all the other stuff, carrying a bit kit can be very burdensome.