Having just done all of this for our upcoming trip:

1. Automatics are considerable more expensive to rent than manuals. Unless you need the automatic, go with the manual. I personally think it is easier to drive in the hills with the manual.

2. You will not need a big car for the luggage with only two of you. I would suggest a mid-size car for your comfort. If you look at www.kemwel.com you will be able to see the various cars and pricing. For the car rental companies, I found kemwel and autoeurope.com to be about the same in terms of price.

3. Depending on the length of your trip, you might find one of the lease deals advantageous. With a minimum of 17 days, you can lease a brand new car through Renault USA or Peugeuot. I think I found Peugeuot through Kemwel, but we found a better deal with Renault. A Laguna 5 door automatic for 18 days is $1539 including all taxes, pickup/drop-off fees and necessary insurance. It is supposed to accomodate four adults, a child and luggage. (We needed the automatic because one of our group is handicapped.) We are picking up at the airport in Rome. They have a desk right in the terminal, and they have the car right outside. The last time I rented a car in Rome at the airport it was a bit of a hike to the rental desk. The person I talked with at Renault when we first rented was able to give me a comparison between the Laguna and a car I am familiar with to help in getting an idea about size.

3. I have Hertz Gold membership, so tried them directly. They were a lot more expensive than kemwel and autoeurope for simple rental.

Let me know if you have any other questions I might be able to answer.

Lisa in Chicago