Hiring a driver for the day

There will be 7 of us going to PV in early August. Has anyone had experience with hiring a driver for the day for this size group? We would be interested in going south of PV and up into the mountains possibly. Do you know what the going rate would be?
Thanks for any information.

Grrr, We just got back yesterday and one day we rented a large Ford van for $120, insurance included. This is cheaper than hiring a large taxi. Simply have your hotel concierge call the day before and arrange everything. Be warned, the guys who deliver the car to your hotel typically run late and are late picking it up! Learn your streets before driving! Go to El Eden south of town about 10 miles. It is FABULOUS!! Email me with questions....