When I am not planning to check in any baggage, I like the Kelty Redwing. It is pretty much the largest backpack that can be used as a carryon and still has a proper waistbelt. (not stuffed to the gills and ALL side pockets empty)

For checked in luggage, I like the Northface Basecamp Duffel. The medium is a good carryon (not stuffed to the gills). The large is a good checked-in (not stuffed to the gills). I prefer colors that are dead bang BRIGHT and UGLY since that makes them easier to see on the luggage carousel. These duffel bags have shoulder straps for short portages and are bomb-proof. For wheels, I use a separate luggage carriers. Wheels are a major source of failure and takes up a lot of space in regular luggage.

Conway Yee