Local shop Jax in Temecula and the Intense Cycles factory crew are hosting a day of riding at Vail Lake. If you have been at Vail, you know you have to pay for entry at the gate. For this day, Sunday the 29th, mention that you're attending the Jax ride and it's free. The event is from 10-4 but I'm sure you could show up early and just say you're there for the Jax Intense Demo for the free entry/parking.
I believe Jax is having a BBQ with beverages at their shop in Murrieta at 5pm
I will be there with my wife and a bunch of friends. Intense should have demo bikes as well. Trails there are pretty good. There's a jump line too if you don' fancy riding uphills much for the other trails.
Here are some of the trails out there.