Is Monthly Car Rental a Better Deal?

I'm looking for advice on a monthly car rental. I'm going to be travelling for business next month and flying in and out of Philadelphia. I'll be there for approximately two months, but will be flying home twice. Would it be cheaper to rent the car for the whole time (monthly car rentals) or do seperate rentals?

I asked Ben for more info on his trip, (dates, times, car size,discounts, any company preferences) so that I could give a better answer with regards to long term rentals:

OK, here's my trip details:

I'm flying into PHL airport on June 4th at 2:40pm. I'm flying back home the evening of June 19th and returning back to PHL the morning of the 21st. I then will be flying home again July 17th - returning on the 19th. My business will be done and I will be returning home the late afternoon of July 31st. I just need a compact car, I'm an Alaska Airlines frequent flyer and I guess I'd prefer Avis or Enterprise - whichever is cheapest! Oh, if I do seperate rentals, will I be able to park the car at the rental lot for free? Thanks!

With Avis, a monthly car rentals rate structure for a 58 day rental was much heaper than doing three seperate rentals.

But, you will not be allowed to park the rental at Avis when you fly home those two times. You would have to go through airport parking -- I checked and there are two options -- garage parking is at least $20 per day and has direct access to the terminals via a covered pedestrian bridge or Economy Parking is at least $11 per day - it is on a lot on the airport with 24 hour shuttle service to the terminal.

With Enterprise, the monthly car rental rate structure for a 58 day rental would be cheaper than three seperate rentals.

Bottom line

Monthly car rentals are your cheapest rate option for your situation. (and you would have to use the airport parking options mentioned above, when you fly home in between.