We are a family of five pax planning to tour Italy for 2 weeks this August. Any ideas for a house or apartment to use as a base and drive around. Preferably at a location north of Rome since we will mostly visit that part of Italy.
Thank you in advance.

You can try an apartment exchange:

Home Exchange International. House Exchange Home Swap

Or you can look for villa rentals in Rome:

Rome Vacation Rentals, Rome Vacation Rental Homes

If you do a Google search you'll get more options.

Good luck and enjoy your trip!

You can try this short time apartment in Rome. Or you can visit this Rome official tourist website, they both have lot of information about any places to stay and any other information that would help you.