I'll save the specifics on sights to see to your favorite guide book. I love the lava tubes though.
I will recommend that you pick your camp sites wisely this time of year though. Stay away from the higher elevation areas or be prepared to spend the night very close to the fire and potentially wake up to some snow. It will be chilly throughout the day, bring warm clothing for both day and night.
I always have an interesting time driving through the deep sandy section of the trail near the OHV area, I find it takes a little throttle modulation to keep up a good speed with the Jeep, but not bounce the trailer (I have an m416) around so much that it goes crazy cutting through the sand. Sometimes the behavior of the trailer is a little unpredictable at higher speeds in the really deep sand, but most of the time its pretty normal, which is what makes those odd ball times so alarming. You'll find yourself saying, holy cow, the trailer is swaying like crazy and I can't even feel it. So keep an eye on it a little more constantly. Still think it would be pretty hard to flip it or anything, but just figured I'd mention it if you'd never driven in deep sand with it.
The water crossing can be deep at times, but the bottom is pretty rocky and has good traction. I've heard one too many stories of hydrolocking engines there, though, so if looks pretty deep that day, its probably worthwhile to get out and depth check just to be safe.
Have fun! It's a great trail, solo or in groups. I've explored much of the area there, including the other trails that branch off the main mojave road. All the trails are pretty tame, and I never encountered anything that gave the trailer a hard time. So, don't be too concerned if you find yourself a little lost
. It's all part of the adventure!