Dave you will love this trip. I spent a semester of college living in London. You will enjoy the Tower of London for sure. I do suggest taking the bus a few times for shorter trips while in London. the Tube( or subway) is great but you don't get a real feel for the city while on the underground trains. I thought they were a little harder to figure out routes but worth it if you ask me. I also saw that you might go to Paris. it would be very easy to take the nearest underground train to the Eurostar train station and go right into Paris then use their subway system once there. then you wouldn't have to mess with rental cars at all while traveling to Paris. the Eurostar is a good experience and a fun way to travel. I was there for 5 months and never got in a car that wasn't public transportation.