Fly to LV!

Unless your group has more than 4-5 adults, it is not worth it to drive from Bay Area to LV. It will take 8 hrs + from Bay Area to LV (basically SF -> LA, LA -> LV). If you book early, you can fly from Oakland (one of Bay Area's airport) to LV via Southwest for about $80 each way. If you drive, it will cost $200+ in gas money and 1 extra night of hotel.

You can drive easily from BA to Lake Tahoe. It is only $250 miles each way.