>From the Michelin site http://www.viamichelin.com/ this is the info you requested:

160 mi in 2h27 (including 130 mi by motorway in 1h48) Departure : Aeroporto Roma-Fiumicino L. da Vinci-00054 Destination : Siena-53100 Departure the: 18/09/2003 Type: Recommended by Michelin Motorway tolls: 5 GBP

You can check the site for complete driving directions. Be sure to use the spelling, as above. An overnight stay en route would not be necessary.

Spagna refers to the Spanish steps. I'm sure there are Ziners who will recommend hotels in that area. We prefer to stay in Parioli at the Hotel delle Muse: http://hoteldellemuse.com/

Cheers! Linda