Jeff,
The 10th at Riviera has an alternate green to the right, which I'm sure is to relieve pressure on the original green, which is pretty small. However, like Adam said, I'de feel short-changed playing such a revered course & iconic hole and not get to play the Thomas green. When I was in Australia, a number of the sandbelt courses have 19th holes and routinely take par-3 holes out-of-play. Kingston Heath uses their 19th hole and takes the famed 10th & 15th out-of-play (thankfully not the day I played!), which again, would irritate me as a paying customer, no offense to the excellent 19th hole built by Mike Clayton.
TK