I know from personal experience that sitting on top of your rollaboard luggage is generally not good for it. Most rollaboards are just not made to support the weight of a human.
I found out that a local company (they're based in Oregon area where I live) has decided to change all that. The company is "SeatKase" and they are making some nice, carry-on sized luggage with a fold-out seat that you can sit on. SeatKase luggage has been tested to hold up to 250 pounds, so it's really tough stuff.
SeatKase uses a patent pending design for the wheels that make them stop rolling when you sit on the luggage so you don't end up sitting on the floor. The luggage is also designed to make it easy to create a laptop stand so you can couple the luggage with any chair that's handy and create an office on demand.
On the SeatKase site, you'll find data on the wheel locking mechanism, as well as ordering and pricing information (the bags are $99 US - a great price for something that looks to be very well made).
I haven't seen one of these in person yet, but this seems like a great idea for road warriors.