There are tons of activities within a few minutes drive. The resort has a spa and nice restaurant/bar area as well as golf. Lake Siskiyou Campground is a 5 minute drive and has a swimming beach and a marina where you can rent patio or fishing boats. There are two high mountain lakes about a 15 minute drive to each. Castle Lake and Gumboot Lake. Both are beauitiful. You can also drive up Mt. Shasta and see the fantastic view from the old ski bowl at about 8,000 feet.
McCloud, an old lumber town, is a 15 minute drive, and offers a very quaint downtown with unique shopping. Floyd's Frosty has great burgers and soft serve ice cream. About 10 minutes past the town, along the McCloud River, are Lower, Middle and Upper Falls. There is a fantastic hike between the three.
We highly recommend the following two restaurants. The Harvest Restaurant (offering upscale dining in relaxed atmosphere) and Pipeline (excellent pub food and beers).
For a true Mt. Shasta experience hit one of the best dive bars anywhere, The Vet's Club. right on main street (if you're going to see a Lemurian is will probably be in the Vet's Club)
Out of towners don't hesitate to ask any of the locals about what to do.
Have a fantastic time!