I've lucked out with my carry-on bag, it's only 1.8kg (3.9lbs) despite the wheels, and the handle doesn't intrude too much. The wheels on two-wheeled models do

I've lucked out with my carry-on bag, it's only 1.8kg (3.9lbs) despite the wheels, and the handle doesn't intrude too much. The wheels on two-wheeled models don't intrude very much, I would definitely avoid the 4-wheeled models, you lose so much space to those caster wheels. I thought about getting a backpack, but my back gets sweaty within a few minutes of walking with it.