I went in 2000 - the year Tiger Woods just won going away. People were trying to dump their tickets for the last round because there was basically no suspense. I went every day including the practice rounds. I still had a house in Silicon Valley where I kept a room and rented out the other rooms.
It's really odd from Monterey to Carmel around a major golf tournament. All the big hotels in the area require a full week booking, even though many don't show up until the official tournament starts. Crowds were light for the practice rounds. I cut my first day short and visited the Monterey Bay Aquarium. It was really lightly visited. I was wearing a US Open cap I'd bought and was talking to an aquarium volunteer docent, who also had a US Open cap (she said she was a volunteer at the tournament too). She told me that visitation was really light because all the hotels rooms were being grabbed for tournament goers instead of the normal tourist crowd. Even once they got there, they weren't likely to visit the aquarium. I've been there on a normal summer day, and it is very crowded.
I also got to see the condition of the course get worse and worse. People were allowed to cut across the greens, and you could see the gradual yellowing of the grass at the designated paths. It was almost like watching the grass die at Wimbledon. I also took a guest to Pebble Beach the week afterwards just to visit the 17 Mile Drive and visit the Aquarium. There were a lot more visitors at the aquarium, and the golf course looked way different. The fairways were cut wider and the rough was no longer 8 inches.