I'm trying to make a curved bench and would like suggestions on how thick you think the top of the bench would need to be to make it strong enough to hold people. Someone has offered to cut the shape of the top out of whatever I choose. then I plan to use something like the Waddell 14" traditional legs or similar square legs, using probably 6 legs. Because it's curved I not planning any support on the under side. Then I will upholster the top (no wood showing but the legs). I have no idea what to use for the top to make sure it's sturdy so any suggestions would be appreciated.

Here's a sketch of the curve with the approximate size. The seat will be 16 inches deep.