I feel so lucky to have found fodor. Thanks everyone for all the valuable info, which helps me greatly for our Sept. Italy trip planning. I ran into some problems while making reservation for san marco. I went through all the steps on www.alata.it. On the top of confirmation page, it showed an error "errore durante I'invio della email a:indirizzo email non corretto o non valido." Does it mean my reservation hasn't gone through?
One more question: anyone has experience with the gondola serenade departing from hotel gritti? It costs 31 Euro per person.

Without knowing the details of how the site work I'd say it looks like you're right -- the e-mail didn't go through.

Basic translation: Error during the sending of the e-mail to incorrect or invalid e-mail address.

Thank you for the help, KT. Could anyone who made the reservations successful share some tips? Anxiously waiting...

Before our recent trip, I spent weeks warring with the alata site trying to get a reservation. Finally, it told me that the basilica would be closed the 2 days of our visit, so I moved up our arrival time so we could see it just before closing time the preceding day. The site would never email me anything, so I just printed the reservation from the screen. On our trip, we raced to San Marco only to find 1)No line at all at 4:45 during prime tourist season; 2)that the basilica would be open the next 2 days--the alata site was just totally wrong and messed up. The next day, we waited in a fast-moving line and saw the basilica again. So, moral of the story, don't worry too much about reserving thru alata. In Venice, keep checking the basilica line, and when it dies down, get in it.

Thank you for saving me from the obsession. We'll go with the flow then and will let you know how it turns out.