The loveliest times to visit the Eternal City are also the busiest and most expensive: mid-March through June (with a spike around Easter), September through October, and December through early January. Hotel prices are generally lower in August, when locals flee the sweltering heat and many restaurants close. Whenever your visit, be warned that those who procrastinate will be punished with less-than-desirable locations and/or price tags.
It's wise to consult hotel websites for possible discounts and to contact them directly—some will offer discounts of up to 10 percent for payment in cash. And as few Roman hotels are standard in room size and amenities, you'll want to be in touch to relay any special requests, like baby cots or even a room on a lower floor in hotels with no elevators. For online price comparisons, the Italian booking service venere.com typically has the best deals.
One alternative is to rent an apartment, especially if you're traveling with children or in a large group. You'll find some of the best deals at rome-accom.com though many landlords require a substantial deposit and cash payment. You could also consider staying in a religious house. The sites go-to-italy.com and santasusanna.org have extensive lists of obliging current and former monasteries and convents.