South Carrizo Creek-Canyon Sin Nombre Loop Trail is a 9.8 mile loop trail located near Julian, CA and is rated as moderate. The trail is primarily used for hiking and is accessible from October until May.
I've made this trip quite a few times. Will probably go again thanksgiving weekend. It's a blast. Fairly easy with a non modified 4x4 as long as you take it easy in some of the rougher parts. The mud caves are one of my favorite parts, I can spend hours going in and out of all the little sections. There are some high points you can climb to, and get a pretty good view around. Highly recommended for a family trip to the desert. Also Aqua Caliente is nearby if you want to hit the hot springs.
Awesome trip to take for a day off road. Its a wash type off road with a few rock gardens, need some ground clearance for the first rock garden.. Love the mud caves and explored in some of them which was amazing. Bring a headlamp if you plan to do any exploring!