I've heard good things about some of the hook-ons, but our only experience is with the following Fisher Price Healthy Care booster - it's actually the only chair we use, both at home and out. We've taken it camping (strapped to the picnic table) and to the grandparents' house. It's not as compact and light as the other options you're looking at, but it's reasonably cheap ($25), sturdy and easy to clean. We haven't flown with it yet, but it's OK for car travel.

http://www.amazon.com/gp/product/B00...SIN=B0000DEW8N