Trolley driver/guides were very knowledgeable and gave us a great overview of the history of Boston. Hop on hop off was great, we could get off to have a look at different places and then get back on when we were ready to continue. Trolleys came every 15 minutes or so. Would thoroughly recommend.
Islands of Adventure at Universal is awesome! Good value for money with the 2 Park hopper ticket. If you can try to stay at one of the Universal resorts you also get complementary Front of the Line passes for most of the rides at the two parks. This will save you a lot of time waiting in queues.
My family and I really enjoyed all of the 6 parks that this ticket gives you admission to. We would definately recommend Blizzard Beach - the water slides there are fantastic. Good value for money and given the queues at the theme parks, you need all seven days to really explore all of the parks.