There are three common routes from LA to BM:
http://www.burningman.com/preparation/t ... o_brc.html
I drove the 5 my first two years and up the 395 through Carson City last year. never done option three, but I've had friends do it and I've heard it recommended to avoid traffic in Carson City and word has it it's a flatter route, for trailers and the like.
My $0.02: if you're driving at night, go up the 5, more stuff open 24/7 that way. Aside from that, I really liked the 395 drive last year and will probably be going that way again. Going up the 5 takes me ~5-6 hours to Sacramento + ~2-3 hours to Reno + ~2 hours to BRC. Last year I think we left LA around 9 a.m and got to Reno around 6, but we stopped a few times for lunch and snacks.
Hope that helps.