ell101706606 wrote a review of Osprey Packs Waypoint 65 Backpack - 4000-4200cu in on August 1, 2012
You can fit plenty in here and it's very comfortable, with or without the hip belt. Plenty of straps to adjust for comfort. I have the large size bag and take it on planes AS A CARRY-ON without any problems from security.
This is the only bag I know of that (a) can be used as a carry on, (b) is 65L, and (c) has a detachable day pack. THERE SHOULD BE MORE BAGS LIKE THIS ONE!!!