Hi Kazzy,
We came back a few days ago. Must sees are of course St. Marks Square and Basilica, do not eat around this area though. Both are free of charge.
Gondola is a must do, we did a 50 minute trip around St. Marks area taking in the Bridge of Sighs for €100. We could have done a shorter trip for €85. Gondelier very informative.
We bought 3 days Vaporetti (water bus passes) they cost us €31 each, well worth the money. Get on the no 1 and do the trip up the Grand Canal and visit the Lido, beautiful. With your passes you can also visit the Islands of Murano for glass blowing and Burano for lace, they are far away.
The Rialto Bridge is a must see even if it is a bit tacky with all the shops.
Becareful where you eat, its very expensive, you need to venture down the back streets. If you like fish and seafood you'll be fine. Pasta in abundunce and Pizza. Not a lot of meat dishes on offer and if there are they are expensive.
There is a Macdonalds and a Burger King in Venice.
Any questions please ask.
Sarah