Good trails betwixt San Fran and Las Vegas

Hello,
Not sure who's still reading here but thought I'd give it a crack.
I'm planning a trip to the Single Speed Worlds in Napa this August and it
almost coincides with a friends trip canyoning/hiking/cycling trip through
Zion and Bryce National Parks.

This leaves me with over two weeks to get from San Fran to Las Vegas in a
rental car so I was wondering what trails might be worth visiting in
between? I'm very keen to visit Yosemite again although not necessarily to
ride. I've been downhilling at mammoth mountain, are there good XC trails
there as well?
I suspect I'll be taking my hardtail so not so keen on the double diamond /
free ride north shore aspect but still like it pretty technical.
Comfortably Numb in Whistler was one of my favourite trails.

Cheers,
Duncan.