You can get a live-in motorcoach with driver(s) but it will be likely something bigger than what most of us consider to be a RV. There are several hundred companies in the business, if one includes leasing agencies for the small one or two coach operations. Operations include regional tours, coast to coast travel, and family vacation trips like the one you propose.
Search "entertainer coach leasing." If you have a particular starting point in mind, try "entertainer coach leasing name_of_city (or state)." I know of operations out of Nashville, Florida, Texas, Las Vegas, and Kansas City.
With the size of your group, what you most likely need is a crew or "roadie" coach, which might have bunks for six to twelve, toilet and shower, a small kitchen, and lounge area. There is a trade-off between lounge size and number of bunks, as the coaches are all physically the same size. These are less posh than entertainer coaches which are designed to provide luxury for 1-4 people, but are leased through the same agencies. My experience is that they are more common, the entertainers often fly, the roadies sleep on the road.
Whether you need one or two drivers will depend on your schedule. There are limits on hours per day and hours between days off. I've been on trips in which the leasing company has had to send out a relief driver to handle the pace of our tour.
Expect $400 to $800 a day for the coach, plus whatever the company needs to provide drivers. You will pay for driving hours, lost hours, driver room and board (it is not customary for the driver to live in the motorcoach), relief driver transportation and travel time. There may be mileage charges in addition to the day rates, and mileage charges for travel to and from base.
Rates for an operation in San Francisco area.
