The trip is too short to see all the islands in full. On Murano: you see glass blow presentation for 10 mins + you get 15 mins to walk in the museum. Nothing to do in Torcello except checking the chirch which you have to pay extra to get inside. Again, not enough time. In Burano you get a little more time, but still not enough. You can get a vaporetto ticket for the day and visit them all at your pleasure. I highly recommend visiting Burano. You can spend there 1/2 a day easily, have a nice lunch with sea food, check the colorful houses and all the lace works.

The boat on the picture is exactly what you get - fits up to 7 people I think. We really enjoyed the tour. The instructions were clear, so we easily found the place of gathering. You can see a lot of Venice from water, get a feel of it. The tour guide was also very knowledgeable. Highly recommend.