Even if you simply wander around without signing up for a tour, the Capitol Complex and the PA State Museum are beautiful ways to pass the time. (But FYI: Touring the Capitol building is completely free, and the State Museum only costs $7!)
Danny and Emily have played minigolf here and had a blast! There is also a minor league baseball stadium for the Harrisburg Senators. (And there are games on BOTH the Friday before and the Sunday after the wedding!)
(Plus, it's free!)
We went here on one of our early dates and loved exploring the gardens and the butterfly room.
We've spent a few dates walking the trails here and have a blast every time. The trails are very accessible and located within the city, so you don't have to travel far at all!
Carlisle has a lot of historic sites and buildings to explore, and several fun shops and restaurants. If history is your thing, you'll enjoy the US Army & Heritage Education Center; and if you're into breweries, check out Molly Pitcher Brewing Company!