I've never seen the 10th at Riv, but I did have the privilege of seeing the 15th at Fenway during my road trip a few years back. I actually got the feeling that it may play slightly better than the 10th at Riviera just because it seemed a bit easier to hit, but that may be because I've seen Riv's 10th during PGA Tour events on TV and that green seems incredibly difficult to hold (I'm going to wait to really formulate an opinion on that until I see it in person, hopefully next year at the LA Open).
Michael, in regards to your comparison to 4 at Spyglass, I don't know if I agree with you. The 10th at Riv certainly has more options off the tee, but there are significant differences. The 4th at Spyglass cuts off driver for longer hitters around 280 iirc, and taking driver, except for the truly ballsy (Phil Mickelson) is not a legitimate option. You are confined to cutting off as much as you want with a 3 wood or an iron, and left with a wedge shot. Meanwhile, the 15th at Fenway does give you the option of driver but a smaller landing area to hit it in. Those who do choose to hit it are left with a relatively simple bump and run, especially to a front pin. Missing left leaves you the most difficult shot in golf: the 30-40 yard bunker shot. Only the strongest hitters can get to that green, but in firmer conditions, it's most certainly doable for long hitters. With a front pin I'd be inclined to pull out the big dog, but a back pin on that top shelf would make me hit an iron off the tee. I'm almost certain peoples club selection would vary for these scenarios.
Perhaps the best comparison I can think of is the 3rd at Camargo: It has a similar tee shot and length, although the green at Camargo is much larger and guarded at an angle front left. Those hitting driver, depending on the pin, could be left with either a very difficult flop shot or a simple pitch. The only difference is there's only 30 yards for you to land the ball where you can put enough spin on it to stop it with a flat lie....leaving yourself more than 85 out means having a significant uphill lie. I hit 3 wood both rounds during my US Am qualifier and was able to get it to stop tight to the pin, while my playing partners only were able to stop one of four wedge shots after hitting driver within a reasonable range. I would imagine a similar scenario for the back pin at Fenway.