Sandy, where are you starting from? I drive between LA and Las Vegas dozens of times each year. If you never hit a traffic slow down and you never exceed the posted speed limit (but travel at the highest legal speed) it requires every moment of a four-hour drive between Pasadena and Las Vegas. (I have been known to do this 3.5 hours -- but see above -- this required driving beyond the posted speed limit -- and a traffic stop for speeding will put a dent in your travel plans).
And, of course, you are blowing past some of my favorite scenic views on any Interstate Highway in America...
As far as lodging goes -- Victorville has the most choices for overnight motels -- there are a couple I'd recommend in Barstow -- not so much any in Baker.
Mark