Hi, I did booked Youth Hostel in LA and San Fran.
The one near Santa Monica is GREAT, cheap price, clean and safe. But the twin private room is always full. I've been there for few days in 6-person room. Usually, we leave very early am and come back very late. No problem la.
For LV, I did booked thru online (e.g. hoteldiscount.com). Remember may have promotion in diff. hotels for diff. period, you can choose some near big hotel e.g. MGM.