I also have a DS14 and a DS12. They have never been big on thrill rides (motion sickness and fear of heights). All these years I would put my kids on the kiddy rides at the annual fair to get them acclimatized to motion in a small way. This year my DS14 didn't go on many of the scary rides with family but managed to find courage when he went the next day with his buddy (first time I would let him go by himself) and he was totally CHARGED by the rides

Now he says he and I will ride all the big name rides at WDW except Mission Space ("when they say they are the only ride to have 'barf bags' they must really mean it"

) and DH and DS12 can stand on the side lines and take pictures!!
If your son typically doesn't like thrill rides (or maybe doesn't like to admit it to anyone because that would be uncool), then try him on Thunder Mountain. That was the one that did it for me. I hated thrill rides as a teen and early 20 something, but then went on Big Thunder and I felt totally secure in the seat because of the seat protection. If he has success with one, assuming it is a fear of rides, then you might coax him on others.
If your son is a gamer, then you have to try DISNEYQUEST!! Any pre-teen or teen into gaming loves Disney Quest and never wants to leave. You may not approve of so much gaming, but its his holiday, too, and if that is what he wants to do for a vacation, then let him have at it. I am surprised that only one other poster mentioned Disney Quest in passing on this thread as a way to entertain a 14 year old boy!!!!
If the family dynamics are a bit grumpy on some days, perhaps he could also venture out on his own for a couple of hours to explore the things he wants to see rather than the "kid stuff" if he wants to do something that doesn't include dragging Dad along. At 14 they like to have their independence, and a couple of hours here or there might be good for him.