Just a friendly tip that in the US we use the word "rent" instead of "hire" - here, hiring is only of people in the employment sense, not of inanimate objects. 
A. If you decide to keep the same rental car for the whole month, here is a thought:
I once asked a rental car company if I could park one of their cars for free in their private lot at a certain airport (it was a car that I'd rented from another location of that rental car company, in another state) for a couple days while I made a sidetrip by flying somewhere else for 2 days from that airport. It was not the location where I'd picked the car up or was going to drop it off, just a random third location. They said that this practice varied from location to location, and I'd have to call that location directly to speak to a manager and get special permission, but sometimes they will do this for customers. (Let you park in their lot for free if you are renting a car with them, but don't need the car for a couple of days.) The manager of that airport location DID end up agreeing to let me do this, which was fantastic, but then there was a huge winter storm and the highway was closed overnight and I had to stay where I was - so I never took them up on it. I would imagine that it would be easier to get a rental car company to agree to letting you park one of their cars without paying anything at a *non-airport* location, because airport parking space in general is so much more at a premium. You would not need to park your car at the airport in San Fran -- you could park it at any company location, including suburbs, so that might be no problem at all for the rental car company. Also, given that you're going to be spending a lot of money in renting a car for an entire month, and the rental car business is suffering with the reduction of business travel this year, I would imagine that they would have more leeway in doing you a "favor" like this. In your case, I would recommend first calling the national customer service number of the rental car company you are thinking of using, because if it's a month-long rental, they might be able to arrange this for you at their level, and save you the calling around.
B. Definitely look into doing 2 one-way rentals.
Last year I often did one-way car rentals. Sometimes it is NOT more expensive than a round-trip rental. Plus, if you won't be using a car for 6 whole days, why pay for it to sit somewhere, esp. when adequate daily insurance coverage is so expensive (I believe that as foreigners you will be required to pay for all the requisite insurances). You will still need to insure the car even when it's not being driven, at least a good portion of the insurance, because you are still liable for what happens to it. But most rental car companies charge more for one-way rentals than round-trip, or don't allow them at all. The best company I found for one-way rentals was National Car. Enterprise doesn't let you make one-way rentals on their website, but you can call and see if they will arrange it for you on the phone.
Also:
The exact spots that you rent a car from and drop it off at can make a big difference. Of course, you'll need a car at your arrival airport, so you are stuck with that location at the start of your trip. However, if it doesn't really matter to you in San Fran where you drop the first car off at or pick the second car up from, I'd search around and find the cheapest location. This can pay off. For example, last year I was renting a car from an airport 75 miles away, to drive to my town. It was a one-day rental (actually, a 3 hour one!). The rental cost from the airport to their franchise location in my town was $75 for one day. The rental cost from the airport to their franchise location in a town 10 miles away from my town was $16 for one day. I booked the rental for $16, and asked a friend to pick me up in the town 10 miles away when I arrived at the franchise there, to drive me home. It wasn't a big deal to the friend, and saved me a lot of money. Another example - last year I had some meetings in southern California. I could have flown into about 5 different airports (LA, Orange Co, San Diego, etc.) and it would have taken me about the same amount of time to drive to where I needed to go from any of them, but the flight costs varied widely from airport to airport, and the rental car costs did too. In one case, the cheapest rental car at a certain airport was so expensive (hundreds and hundreds more dollars than what the rental cars from an airport 25 miles away were listed for) that it was going to save me money on the travel plans as a whole to pay for a more expensive flight in order to fly into the airport where the rental cars were so much cheaper. And I discovered that, for the date that I needed my car, some of those California airports' rental car offices were fine about one-way rentals, while other airports' rental car offices didn't offer one-way rentals at all, or charged an arm and a leg for them (this was all with National car rental - the same company). |