Pearl Harbor—I'm told it's the only place that spends no money at all on advertisement and yet still gets over a couple million visitors a year. Having been there, I can understand why. Knowing this, expect a crowd, regardless of what day you visit.
To get to Pearl Harbor, get a guidebook. The traffic is heavy and the directions can be tricky, but having a navigator read while someone drives does the trick just fine. Once in the parking lot, head to the LEFT (while looking towards the water) and get in line to get your free tickets to the memorial. Parking was free, the tickets were free, and they offer headsets that are giving a good guided tour of the museum, which I THINK were free too, and if not, they were a well spent $5.
Get there EARLY! The line soon gets very long, and you can have a long wait till your tour. The last tour is at 3pm (or so). Tours last for 45 minutes. While waiting for your tour, visit the museum (and listen to your headset)—it makes the time go by quickly and is ideal for learning the history. There are restrooms and vending machines at this location, and a small gift shop.
Once your tour is called, you get in line to watch a short movie detailing Pearl Harbor, then hop on a shuttle boat to the Memorial itself. You only have 15 minutes there, and it goes by quickly. Look down at the Arizona under the water, see the oil drops leaking, and bring leis if you'd like to drop flowers in the water in memory. Go to the back and see the list of names, checking to see if you share the last name with anyone who perished (we did). All too soon you're on the shuttle craft back. It's naturally very quiet at the memorial out of respect for those who lost their lives. The feeling you get there looking down at the battleship is one I've never felt before, and very hard to describe. You'll most likely feel it, too. I think most everyone does.
In the museum area, there are often survivors of Pearl Harbor who volunteer their time there. Feel free to talk to them. Take some time to look at where the battleships (and others) were.
If you have time, go see the USS Bowfin (sub) and USS Missouri; both are accessible from the same parking lot, but to the RIGHT of where you parked (while looking at the water). Both are well worth the history lesson, though the Bowfin does not allow kids under 4 to tour.