I have had really good success with my 55 fitting in the overhead bins. The only time it didn't fit was on a small turbo prop plane. They had to gate check it.
Yes, keep in mind the little commuter planes if you are carrying that bag.
I had a flight on one and got a bulkhead seat, which meant no underseat storage. Rude flight attendant grabbed my Cosmic Blossom PM (with laptop, wallet, etc inside, mind you) and started shoving it in the overhead about halfway back the plane. I tend to be protective of my bags (and my husband would go nuts if he saw the laptop being treated like that) and I politely asked if it could go in the coat hanging area nearer to me, and she flat out said no, that's not for passenger use. No more than one minute later, she takes a larger laptop bag and jacket from another passenger and hangs it nicely inside. Harumph!