Every car has air conditioning. Every car will be an automatic. GPS can be added, or you can bring your own from home and pre-load California maps.
Try http://www.CarHire3000.com , http://Hertz.co.uk , any 'local' 3rd party car rental, any major car rental website (be sure to tick the box that indicates your home country), or even a local travel agent.
"Fit" 4 adults is a personal choice. Suggestions include a full size SUV, a mid-size SUV, a minivan, a full size car, a mid-size car. Look at the descriptions and see what appeals to you, then ask here for specifics. For example, I was unhappy when we were offered a full size car with tiny windows for the back seat passengers, even tho' there was plenty of space for people and luggage. I chose a slightly lower quality car instead and had great views instead of plush seats.
Off topic ~ have you booked your lodging for the busy Labor Day weekend already?
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Is there a Tardy Typist tiara for this forum? If so, I think it's my turn.
Edited: 12 years ago