4.5 stars, rounded up for the resort as a whole and good value.
I've stayed at the Palazzo before, and obviously the suites are comparable (pretty much the same, except for location within the resort and room decor). We booked a Bella suite through Jetsetter for a very reasonable price. For me, the main appeal of staying at the Venetian & Palazzo hotels is that they offer suites with two queen beds (instead of one king) as well as a full pull-out bed. Because of the additional bed options, I think the Venetian is one of the best-valued hotels for larger groups.
Room: We stayed in the Venezia tower, which was built later than the other tower but has a more "classic" decor (more in line with the hotel theme & a little less modern). I liked the decor just fine, but I actually really liked the location of the Venezia tower. The elevator is right by the front desk and valet / taxi line, which was very convenient for us (no walking a mile through the hotel in heels just to get cabs!). It does take two elevators to get up to your room (there is a separate elevator that just takes you to the Venezia tower lobby), but I didn't really care. The rooms are also in the same tower as Bouchon *drool* - so if I had the option again, I would definitely choose a room in the Venezia tower. As far as the suite itself, I was very pleased with everything and have no complaints. The room is spacious, the beds are comfortable, and the bathrooms are clean and updated. There is a powder area inside the bathroom, which is useful; however the shower has clear doors (so depending on whom you're with, you may only be able to shower & use the bathroom one at a time). Also, one difference I noticed between the Venetian and the Palazzo: the suite I stayed at in the Palazzo had an L-shaped couch with a pull-out bed, whereas the Venetian suite had a regular couch with a pull-out bed. With the L-shaped couch, you still had half of the couch when the bed was pulled-out; in the Venetian suites (at least in the Venezia tower), you lose the couch once you pull out the bed.
Service & amenities: The front desk and concierge staff are great - friendly, welcoming, and helpful. I had no problems and they were for the most part, timely and efficient. Our room was just a short walk away from the casino and the Grand Canal shops. Bouchon *drool, again* is located inside the Venezia tower and actually offers cocktail and food service in the summertime at the Venezia private pool! There are also two fast food courts located within the hotel (cheapest restaurant is probably Panda Express). Both hotel pools are nice, not too crowded and pretty quiet. For a livelier atmosphere, you also have Tao Beach, which I'll review separately.
Location: The Venetian is in a pretty good location on the strip. Getting in and out of the hotel from the Venezia tower isn't overly complicated, and there are also a few walkways you can take to get to the Palazzo and the Wynn/Encore pretty easily. It's roughly a $10-12 cab ride down to the Cosmopolitan, ~$5-6 to Encore.
Overall, I enjoyed my stay at the Venetian and would book a room here again. As a complete package, the Venetian/Palazzo resort offers a lot of entertainment in one convenient location.