I would recommend these:
http://travelstore.ricksteves.com/catalog/index.cfm?fuseaction=catalog&parent_id=8
They are bullet proof, have hideaway shoulder and waist belts so you can carry/hike with it if you need to, they are soft so fit almost anywhere, and are the right size for carry on in an airplane. I have dragged this thing all over Europe over several years it still looks like new. I think some have rollers but mine doesn't. It is a perfect fit in front or back trunks and because it is soft you can load lots of other stuff in the trunk with it and it will still fit.