For the four of you it would be better IMHO to get a private taxi. I would go out to the road and get one rather than arranging one through your hotel as I found that it is cheaper to do so. (just my experience), in some cases it may be the same price.

Don't be afraid to negotiate a price (it is expected that you will do so). More often than not the first price quoted by the driver will be WAY WAY WAY too high.

Make sure that the FULL cost is CLEARLY agreed upon before stepping foot in the cab so there is no surprises later. Some cab drivers will be willing to wait for you while you are at Rick's and will drive you back to your hotel. If they offer that option then make sure you agree on the full cost of that as well, in advance.