We went to Pearl Harbor, on a weekday, and did not find traffic difficult- it keeps moving at the speed limit. We found that following the speed limit is typical (unlike other cities we've visited). We had one (thought it was better than none) advance purchase ticket, but didn't need it. They gave us three tickets for 1:30, which was 2 1/2 hours later, so we left, went to eat nearby (did some shopping at BestBuy and Goodwill [lots of sporting goods for kids, perfect to buy and give away] then returned. Parking can be full but people come and go often. Leave all bags in the car or you'll have to walk them back or pay for a locker.
Go to the north shore, if possible. It's incredibly beautiful, perfect size waves in June/July for children to play and not get beat up. The slope of the sand is perfect too. Wear shoes to walk in the afternoon as the sand gets hot. There are feral chickens all over Hawaii, it's fun to watch them up by the vegetation. Dole plantation is something to see- a total tourist trap, but you'll likely never again see so many pineapple-themed items. Even if you aren't into pineapples, it's right on the way to the north shore, is free parking, and has great lotions to sample. They make you smell like a pineapple, however.