Oops my bad... I failed to see that the OP was looking for a wheeled bag.

Anyway, along with the highly regarded B&R U116 which it seems many swear by around here, you may want to check out the Tumi Wheeled Compact Duffel (http://www.tumi.com/product/index.js...ndSrc=paramNav). I own a previous gen of the same model and it has served me well for certain situations. I feel that both the B&R U116 and Tumi Wheeled Compact Duffel provide very good bags with a single large cavernous space.

For me, though, when I use a wheeled bag for my laptop and other electronics (for smaller planes) I use a Tumi Compact Wheeled Brief (http://www.tumi.com/product/index.js...ndSrc=paramNav). It has a very small footprint but fits a ton of stuff inside... When fully packed, I can fit my 15" retina macbook pro, ipad, earphones, chargers/cables, and a notebook and pens/etc. It's also expandable but I've yet to use that feature since I usually travel with two bags with one for electronics and the other for clothes/etc.

I also tried the Victorinox San Marco (http://www.swissarmy.com/us/product/...-Case/31323101) but ended up selling it in favor of the Tumi mostly because I felt there was more usable space for me.

I think the choice will really come down to intended use. If you're looking for one bag travel for general use go with the B&R U116 or Tumi or if you're looking for a briefcase dedicated for a laptop and electronics then go with the Tumi or Victorinox mentioned above.

All of the bags mentioned should fit fine under a seat, even on the smallest of planes.