« on: December 28, 2011, 11:27:50 AM »
1 lens solution. Canon 15-85 IS bolted onto your 450D. Simple, light, versatile, great image quality.
3 lens solution. Your 450D, your Sigma 8-16, then add Tamron 17-50/2.8 (or Canon 17-55/2.8 IS which is heavier) plus Canon 55-250 IS.
My travel setup is similar to the 3 lens option above. I used it in SE Asia for 3 months this year, plus another 1 month in the U.S., plus another 1 month backpacking at home in Canada. I've used a similar setup for a cumulative of at least 18 months on the road over the past 5 years.
Your 450D is a camera capable of great photos. No need to upgrade to something heavier.
Enjoy your trip.