Do not use aragonite. Use either play sand or pool filter sand. I personally prefer pool filter sand. It can be bought from any pool supply store for about $10 for 50 lbs. Just make sure you clean it really well before putting it in the tank.
To do a gravel vac, you don't do it the same as gravel. Some people just wave the end of the vac above the sand to kick up waste. Then they suck it out. I push the gravel vac at an angle about 1/2 inch into the sand. It picks up some sand, but since the pool filter sand is heavier, if I wave the vac, it will fall back into the tank.
Pro- Waste sits on top of the sand, it doesn't build up in the gravel. It looks more natural. Fish love to play in it. Easy to maintain.
Con- May be cloudy at initial setup. It depends on how well you clean it. Depending on what type of sand you use, it can be pulled into the filter. Again, the heavier the sand, the less likely it will get pulled up.