The bridges really feel alot more like a driving on a highway that just happens to be over water, if that makes any sense. They don't feel very high. Also, you will be so preoccupied by the spectalular view you won't even notice the bridges.
If you can possibly find the time time to take the day trip out to the Dry Tortugas, I highly recommend it. It's one of the most beautiful places I have ever seen and is something your 7 year old would probably really enjoy. The snorkling is good there if you're into that and walking around the sea wall around the fort, you can see all kinds of sea life without even getting in the water.
Have a great time!!


