George,
Since no one has spoken of BB let me be the first.
The fourth hole can play as a short par five of 460 yards from the lower front tee, to 535 yards from the top back tee. For even the most accomplished of amateurs, this change will present different challenges and strategies. The hole will still play as a world-class par five at any of the distances.
The seventh hole is monstrously difficult as a 595 yard par five from the true back championship tees. As a 510 yard par five from the front, it is still all that most can deal with, as the temptation to play down the right side thinking one can hit it past the trees will usually put one in the thick rough.
The front tee on ten allows most good players to have a chance at this hole. It actually causes many to play right into the rough as it points directly towards it. It takes an intelligent player to shoot left, and still the second shot to the green is difficult when the pin is right and along the bunker. Back left though, I believe is the tougher pin position when played from the front tees, as many a shot is not held and rolls over the green into heavy rough. As even the pro's had a difficult time from the back tee, which are over 100 yards behind the front tee, this may be the ultimate "adjustable" par four. That is until you come to number 12.
12. This may be the ultimate great "adjustable" par four in the world. The front tee has the hole playing about 400 yards. The carry over the cross bunker is still difficult for many, and no matter where your drive ends up, the shot into the green is still going to have to be very well struck to place your ball on the same level as the pin, especially if it is front left. Playing from the back, the hole can be stretched to as much as 520 yards in length. This hole is also among the greats in the world.
15. Oh wait, 15. Now THIS is truly the greatest "adjustable" par four in the world. From the front tee, it measures as the longest 410 yard par four with the green up the hill on the side of the cliff. The back tees, measuring out at almost 490 yards were too much for even the best in the world to deal with. The USGA wouldn't even consider playing from there during the Open. This hole had the players calling it the "most difficult par four in the world" during the Open. Davis Love III even said that the contours of this green were more difficult than any at ANGC! This is among the best holes in the world (IMHO).