Karen, (assuming you haven't had a chance to visit Rome very extensively) is there any way you can spend at least 2 nights in Rome? Considering the long flight etc. this would be so much better for you than just one night. There's so much to see.
We used
www.romashuttle.com (as many LCTers have). They were the least expensive but we had punctual pick-up in an air conditioned Mercedes with a very interesting English speaking driver. I think the cost was about 100 Euros.
