I just watched National Treasure and enjoyed it more than I've enjoyed a film in a long, long time. It's the perfect Borepatchian film: full to the brim of history nerd clues and puzzles to figure out and with the happy story about happy people with happy problems ending that I like. It also has Sean Bean (who doesn't die in this film; go figure) and is perhaps the most I've enjoyed Nicholas Cage since Moonstruck. It's kid-friendly, too (as you'd expect from Disney).
If you haven't seen this then you're in for a real treat. Highly, highly recommended.