Mostly to avoid long lines, we are thinking about buying tickets via the on-line services offered. In particular, we would like to pre-purchase the tickets to the 'major' attractions: Coliseum, Vatican, Duomo, etc.
1. Does this REALLY save waiting time once at the attractions?
2. Besides 'locking' us in for specific day/times, are there any other downsides to do this? (A slighter higher price is not an issue for us either, if it helps accomplish our goal of eliminating wait times.)
3. Any recommendations as to what agencies to use not/use?

Thanks!

I am in the process of doing the same thing. I paid 16E each for the Secret itinerary tour in Venice (I think SelectItaly.com). For the Uffizi, go to weekendafirenza.com--it's 30.40E for two tickets, less than the 42.40E I paid on another site (www.florenceart.it).

You can reserve the Accademia Gallery in Venice on their site, gallerieaccademia.org for no service charge.

In Rome, I've read good things about www.ticketeria.it for the Borghese. You can go to the Vatican site to get a tour for the vatican museum. type 'Vatican Museum' in the search field on this board to get the web address.

hope this helps!

it is totally worth it... for the big attrations. the smaller ones, not so much.
the Accademia (The David) in Florence as well as the Uffizi are essential to get in advance. we got our tickets and waltzed right past all the lines - it was great! the Duomo we kinda did on a whim, so i don't know if its worth it or not. w/o reservations we didn't wait too terribly long.

i don't believe you can reserve tickets for the Vatican Museums in advance. my advice, what worked for our group, is to get there EARLY in the morning. 745-ish.

to get the lowest fee, i had to CALL the Uffizi offices in Florence and make the reservation (+39 055294883). she spoke english - no worries - and was able to make my reservatins for the Accademia, too.
on our tour day, we arrived at the ticket counter as instructed, paid w/ cash (only method accepted) and by-passed all the lines. it was so easy i thought we'd done something wrong.

Vatican Museum
Actually, you can reserve a tour of the Vatican Museum from the Vatican's site...you just have to fax your request to the phone number listed. I think this may be new, but I found out about it on the ST Italy board (thanks, guys!)

You know, I was in Italy in September, 2002, and except for the Vatican, I didn't have to wait in line more than a few minutes, so I didn't find prepurchasing useful. I'm returning to Florence in May, and I'm not making any advance reservations for routine museum visits.

S Tenen, With all due humility, I suggest you rethink your policy, at least for the Uffizi. In May, the lines can be hours long. And if your last visit to Italy was in 2002, I think you will be absolutely amazed at how many more tourists are now flooding Florence, Venice and Rome.