This is a great property if you like peace and quiet. Not so much if your into the night life.
The casino on property is moderate to smallish with 6 deck shoes at the blackjack tables. It's also easy to ignore if you're not into gambling. Otherwise you need to make the 30 min. drive to South Shore for large casinos.
This is a great property for families, with a heated pool, family and adult hot tubs, and a private beach. Its also a great romantic spot with fantastic views, good dining options, a very nice full service spa, and the previously mentioned adults only hot tub.
As a Diamond on a paid rate, you'll get standard room on the Regency Club floors (11 or 12). Ask for a view of the pool, as the Mountain View actually overlooks the parking lot. If the RC floor isn't available, they'll give you access without any hassles. Don't expect a suite upgrade unless you pay for it.
You can also run a search on the forum for Lake Tahoe. There are several trip reports.