My community tank has gravel and my cichlid tank has sand, so I have current experience of both.
The gravel is reasonably easy to clean with the gravel-vac, and you'd be surprised at how deep the dirt can get. Only thing is it's not always that easy to see just how dirty the gravel is until you actually start cleaning.
The sand looks reasonably good, and the fish poo mainly just sits on top. It's true that you can suck up loads of sand when using a gravel-vac, but as already said just move the vac around to stir up the dirt a little and it will be sucked right up.
If you do some reading on how to use sand in an aquarium, you'll find that the anaerobic pockets (areas of sand that contain poisonous gases) only develop and become an issue when you have such a thick layer of sand that oxygen-rich water cannot penetrate it, and organic matter gets deep enough to rot without oxygen. I believe that the general guidance is that sand thickness of up to 2" is enough such that this problem is avoided.
Hope that's accurate and of some help.
Irf.