I converted my 40 gal over to sand this past week, and it wasn't that bad.
On Wednesday i did a water change and before filling it up, i took about 98% of the gravel out with a net. Then on Saturday i put Tahitian Moon sand, looks great.
a few things i picked up in the process:
1. you don't need as much sand for your tank to look nice, i have about 1/2" to an inch of sand.
2. the Moon sand is heavy enough that it does float around, you can pretty much get your impeller filters running right aftr a water change..
4. With black sand, all your fish crap and food scraps just sit on top of the sand easily visible.
3. Vaccuuming is a breeze with a Siphon Kleen, when gently combing over the sand, the suction is strong enough to pull fish crap out of the tank, but not strong enough to pull the sand out of the tank. I just have some sand swirling around the bottom inch of my siphon kleen while kleening.