I've done that, I never carry a rollybag in Europe or other countries where there aren't escalators and wheel-friendly paths. (Pretty much everywhere

) Dragging a wheeled bag over Prague cobblestones or up and down Barcelona Metro train stair-mazes... nein bueno.
Osprey Porter series backpacks are well-reviewed for the sportier looking crowd. I run Arcteryx (Khard and Blade 21), Patagonia MLC (too soft though - bad support), and Osprey Porter 46 (almost perfect for me.) I don't have any Red Oxx or Tom Bihn, but they seem well received for a little dressier folks.
Features to consider / look for: panel or full zip opening. Top loaders (like the classic "book bag" backpack means you gotta pull everything out to get to the bottom. The duffle type full zip allows you to access everything at one glance. A separate dirty laundry or shoe compartment is a plus. Small accessory pockets on outside are good for tickets, sunglasses, etc. Lockable zips a plus if checking or leaving in unsecure areas. Get decent, but not too burly, waist and shoulder straps. Too big and it's a bulky mess. Too small and they cut into your shoulders. Osprey and Arcteryx do this well.
Do do laundry at hotels and long stops, pack reusable wrinkle free clothing, bring stinkproof dirty clothes bag to separate wet swimsuits and odorific socks, etc. from rest of bag.
Travel a few times without the wheely bag and you'll be hooked on that fastmover non-overpacking life.