Had exactly the same problem. Need a roller / carry-on / suiter (garment bag). I considered:
Tumi Alpha:
Wheeled Carry-On Garment Bag - Tumi
Victorinox East/West:
Victorinox Luggage - WT East/West Carry-On Garment Bag
Briggs & Riley Baseline:
Carry-On Wheeled Garment Bag, U174, Baseline Collection | Briggs & Riley Official Site
For me the problem with most carry-ons (except the 2- or 3-fold true garment bags) is that the suit shoulders get folded/pinched in because the bag isn't wide enough. I narrowed down to the three above because they: 1) carry suits 'width-wise'; 2) are long enough to not pinch suit shoulders; and 3) use the full length of the bag to accommodate suit width. Plus they're nearly bulletproof.
I ended up choosing the Victorinox and am very happy with it. Got mine from Altman Luggage:
Luggage, Carry On Luggage - Altmanluggage.com
They're currently running specials on some items, are offering an additiona 10% off, and free shipping (at least at these price points).