I recently bought the 18" Carry-On Expandable Upright (U418X) and used it for a week long trip to Venice and Amsterdam. No issues with size, even on a KLM regional jet it fit in the overhead, but that may no be the case for all. I wasn't using the expandable feature at the time.

I've been using a 22" Carry-On Upright (U422L) for the last year on my domestic flights, and it fits wheels or handle in first on many planes, but not on all planes. I expect that if the airlines start cracking down, I may be forced to check it at some point as the wheels and the handle are probably what would make it too big.

Both are well made and lighter in weight than a similar size piece from a membership warehouse that I had been using for the last 12 years.