I have two bengals, and it sounds like your guy is fairly typical for the breed. I agree with the others who said it sounds like he is bored. The good thing is, this is easily cured.
If you don't already have it, I hghly highly recommend a toy called 'Da Bird'. It's basically an interactive fishing pole type toy with feathers, but the way it flies does look a lot like a real bird. If you want to see your bengal act like a wild cat, hunting, stalking, jumping, this toy will get them going. My bengals play with this like no other toy, jumping 4+ feet in the air to 'kill' it, running around like lunatics, stalking it, just having the best time with it. They will play with this toy til they're too tired to play anymore, and even then they won't want to quit. It's hard to be destructive when you're tired out!
Another thing that bengals really need and love is things to climb on. Do you have a cat tree for your boy? If not, you definitely should invest in one. If you can't afford one of the big expensive ones, Wal Mart has a cheap floor-ceiling one for around $30. My guys like this one just as much as the 'better' one. I also rearranged a spare bedroom to make it almost like a climbing course for the cats. They jump from the cat tree to the bookshelves, back to the tree, to the top of the dresser, onto the bed, etc. This is another great non-destructive way for them to release their energy.
If your cat is still being destructive, you may want to consider a playmate. As good as you may be at playing with your cat, no one can play like another cat can.
If none of this helps, you may wnat to consider trying Bach flower essences. You can buy these in any good health food store, or online, and some people have had great success with them. I have used several of the essences for different things with my bengals (and other cat), and they do seem to help. I believe Vervain is the essence for calming, but even regular rescue remedy may help. They couldn't be simpler to use either, you just drop a couple of drops in the waterdish. Here is a site if you would like more information. http://www.bachflower.com
If all else fails, please do not have your bengal put to sleep. There is a bengal rescue network (http://groups.yahoo.com/group/bengalcatrescue/
) that helps bengals in need find new homes. If it comes to the point where you just can't deal with him, please consider contacting them rather then the alternative. You can also e-mail me directly if you like, and I will help you any way I can. My e-mail is email@example.com