My wife, then girlfriend. On our first mini vacation together. We visited the Freedom Park and Navy Museum in Omaha, NB. If you have kids this is a fun place to go. Admission is free, so it is affordable. You get to see naval parts even an old submarine and old canons/guns. Many of them you can touch or climb on. It even brings out your inner child as an adult.
If I remember, they give tours of the submarine at certain times. But, there were not any scheduled that day.
My wife showing off her canon skills ready to defend Omaha.