just wanted to add...

I always carry a 22" rollaboard and a fairly large computer bag. My rollaboard goes in the overhead bin wheels first. My computer bag goes in front of my feet (unless I am in a seat without a seat in front of me. Once the plane is finished loading, I move my computer bag to the overhead bin if there is room left.

I do this to be courteous to other passengers, a courtesy that is often lacking. Since I get to board in the first group, there is always available bin space, I just don't take advantage of this.