I have had about twenty apple snails in my life... my favorites were one that I think was a golden apple, and was about 2 1/2 to 3 inches around (little smaller than a raquet ball) and the little marks on his foot, I called them topigraphical, not sure what they are, were a vivid electrib blue. That snail, and another one I had routinely laid eggs on the bottom of the glass hood for me. The other snail was absolutely huge, larger than a baseball.. I have no idea what he/she/it was, but it was awesome, lived for about 4 years in my care.
I currently don't have any, though I am going to get a few to keep my wifes goldfish tank clean. I had two in it before, but went away on vacation for a week and forgot to put food in for the flock of goldfish... they thought the snails were suitable substitutes.
now, I have gotten her down to one Gold Moore, and were putting him in a 30 all by his lonesome with a couple of apples.
In the past, my favorite snail for a planted tank, are malaysian trumpets, they breed rapidly, and control all types of algae without damaging your plants...