24 X 12 X 4 is a nice piece of wood, and to start , I wouldn't suggest cutting it up. A nice piece like that is too hard to come by for a solid carving.
As to what to carve, study it. Let it sit on your bench in various attitudes......horizontal, vertical, turn it every so often 90 degrees to expose all the sides, and just study it.
You could try photographing the piece from all angles/sides and e-mailing a few folks the pictures to get their opinion, or post them here for general opinions. Some folks will be more inspired with ideas by actually looking at the wood.
Suggestions of what to carve ........ to start with, you could always send it to me, I have just the image in mind for a piece that size!

Otherwise ....... it would make a great ships hull carved with all the detail, or a nice deep relief carving, (nautical scene of course), or a carved small table top, or a small shelf mantle with a carved edge, or a soldier/warrior standing. I could offer more once I had seen the piece of wood.
Bob ....... envious of your bounty!
