Welcome aboard the RoadTrip America Forums!
What you want, I believe, are the booking search engines such as Travelocity, Expedia, Orbitz, Kayak and the like. These will let you see the total prices (for the car and one way drop-off) from half a dozen or so of the major car rental firms. The price quoted will usually include taxes and fees as well, but NOT fees for additional drivers or insurance, since those are things that you normally sign up for at the point of getting the car. I did a quick search for three weeks in June-July of this year and am being quoted prices between $1,700 and $2000 depending on the company and type of car. You will have to check with the individual companies as to what their charge for an additional driver is, but often if it is a spouse, there is no additional charge. As to insurance, you should check with your own underwriter to see if your current coverage extends to rental cars that you drive. It is also worthwhile to check with your credit card companies to see if they insure you when you rent the car on their card; many do. And if you are a member of RAC or AA, they many also extend you coverage. Just don't buy coverage that you already have. Not only won't you need it, but in the event of an accident, it will just complicate things as everyone tries to get the other coverage to pay for it. Finally, you would be hard pressed to rent a car in America that did not come with an automatic transmission and air conditioning and, except in the cheapest models, cruise control and a CD player.
AZBuck