If you really don't care about cost, go with the Cipriani -
http://www.hotelcipriani.com/web/ocip/ho… This is top of the line by any standards.
If that breaks the budget, then the site I use for hotels here in Italy is:
http://www.venere.com/italy/venice/ . I live a couple of hours away from Venice and stay over for Carnevale, Il Redentore, or the Biennale sometimes. A couple of places I like are:
Hotel Selvadego
http://www.venere.com/hotels/venice/hote… and Hotel all'Angelo
http://www.venere.com/hotels/venice/hote… . Both of these are very close to Piazza San Marco. The Selvadego is a minute or less on foot.
A couple of places I like to eat include:
La Zucca in the Santa Croce area:
http://www.lazucca.it/
Da Raffaele between San Marco and Accademia:
http://www.ristorantedaraffaele.com/
and Bistrot du Venise between Rialto and San Marco:
http://www.bistrotdevenise.com/eng/index…
Da Raffaele is especially nice when you can get an outside table and eat while the gondolas pass by. There are many other possibilities - check the menus while you're out exploring to pick places that appeal to you. Of course the restaurants at the Cipriani are excellent and have a great view of Venice.