I love going to Castle Park. It's cheap and fun. I don't care much for the arcade and have never gone near the batting cages, but when there isn't much to do on a warm evening, this place is a great option.
A round of mini golf is about $6.50 for an adult and there are 3 courses to choose from. There are a lot of neat decorations to look at and and the courses are pretty challenging. They are also open late, closing around 11 or 12 on the weekends.
If you go before noon they offer a discount, as well. Just beware of Sat night crowds that can keep the courses backed up..