I have three of these bags now (17, 24, 28) and I use the two smaller ones the most.  If I were to completely fill the 28", it would weigh too much to check at the airport, even though the luggage itself is very lightweight!  The 24" is perfect to check and the 17" is great as a carry-on.  I only wish that I had found this luggage sooner....its' light-weight and spinner wheels make my travel-life so much easier!