I've done the drive several times. It can be done quite easily in a full day with a couple of short stops, but personally I have always stopped off overnight at various places due to planned visits to sights or resorts en-route. However, Rainboe does have a point. Do not underestimate the distances involved and if your wife is not fully enthusiastic about a lengthy car journey, then the alternative of flying may be a sensible thing.
If you do decide to drive, there are many places of interest dependant on the route you take and your individual interests. However, I would warn you that whichever route you take, the last 100 miles or so is through the Mojave desert which must rate as the most boring drive you will ever take.
My recommendation to you would be to ask yourself what is the purpose of your holiday. If the primary purpose is to see San Fransisco and Las Vegas, then fly. If it is more of a touring holiday then take your time, take in some of the many well worth seeing sights and drive.
If you decide to drive PM me and I will recommend some optional routes. Whichever way you go you will have a great time.