It does depend on his maturity, but if your budget will stretch to it I would suggest the Boardwalk. There is a pretty active evening entertainment where he/you could walk about. It would be particularly good if he managed to buddy up with someone of a similar age as it's a pretty controlled and contained area but still has a "buzz " to it. Slightly cheaper but in the same area are the Swan and Dolphin hotels (maybe 5 minutes walk). The Yacht and Beach club hotels are also in this area but they are at the higher price range.
If you feel he is VERY mature then you could look at either of Old Key West or Port Orleans resorts. Both of these have water taxis and bus services that run to the nearby Down Town Disney. Non Disney hotels in this area are Hilton, Double tree, Courtyard by Mariotte and a couple of others. There are a load of shops and restaurants in this area and again there is a real "buzz" about this area. The downside is that there are a lot of local kids/young adults in this area and you may not feel you'd like him to be in this area on his own. It's a tough call at this age (14-16) they are usually used to a certain amount of personal space, but that is usually in an area that they know and are familiar with what does and does not pose a danger. Out of their own "turf" presents different problems and it is certainly easier for them to get into a situation, without knowing the easiest route away from that situation. Personally I'd only let my kids out and about at DTD if there was more than one of them, but both mine are girls so maybe I'm a little more protective. Even if you don't feel happy about letting him out for an evening at DTD, you could let him go over there for an afternoon if you wanted to laze by the pool. It would give him a little freedom while minimizing the risks. Midweek would have less locals about than at a weekend.
