...does it fit under seat on most (domestic) planes? I'm guessing that it might be a bit tight to fit, but wanted to get some feedback. To be specific, most of my flying is on United, and I'm not even considering those seats with the stupid entertainment boxes underneath

I'm going to be taking a lot more short trips and want to upgrade to a single bag vs. the standard small laptop bag/rollaboard combo I've had for a while now. I'm really liking the Tom Bihn bags, and trying to decide between the Tri-Star and Western Flyer, and would really like that extra 3rd large pocket on the Tri-star.

I don't necessarily need my stuff in front of me at all times, but I typically board later (either rushing to get to flight or by choice b/c I'd rather sit in the club than rush onto plane first while every person after hits me with their bag as they board) so I prefer to not have to even think about whether I'll have overhead space or not.

Thanks!