Unfortunately there is no one-size-fits-all solution to packing and choosing suitcases. My first year in country I always traveled with backpacks, even though my village has some paved roads and even the unpaved are just dirt--not really sandy. And I was really hurting my back. Then I realized I had a carry-on size rolling bag and I started using that for trips into the capital, to other peoples' villages, etc. In our buses, they have places to store bags underneath so it was easy to do that with my bag. I agree with Shawn--very important to have at least one backpack so you can carry things easily. But having an option of using rolling bags is also not a bad idea. You are definitely NOT wasting your time with rolling bags. But again, it is all country and site-specific. I know friends who lived in the Kalahari desert who stepped in 6 inches of sand on their way from the bus stop to their house. So a rolling bag wouldn't have worked for them.