Pete,
Well said...Do you think that the best driveable par 4s use hazards that don't present penalty strokes (water, lost ball, OB) as part of the risk? Obviously, you mentioned the 10th at Riviera, which is widely considered the best driveable par in the U.S. for Championship golf. The uphill "5 and dime" hole at Ridgewood also comes to mind, with its miniscule green benched into the side of a hill surrounded by rough and bunkers.
It seems that looking at a driveable hole, the player sees a water hazard as much more penal than the angles, small green, and bunkers that make Riviera's 10th so hard. However, while the players aren't going to incur any penalty strokes at Riviera's 10th, they make all kinds of messes there. If you watched this year, the pros had all sorts of trouble even making 4.
In my previous post, I mentioned the driveable 4s at TPC River Highlands and TPC Scottsdale, and both have water around the green. They seem to work well for the tournaments and provide some excitement. It doesn't necessarily mean that they are great examples of short 4s...