We want to meet up with our friends who live in Baltimore. They have a 2.5 year old, we have a 2 year old. We don't want to drive 5 hours and we don't want them to have to drive 5 hours either. Where should we meet up in the middle that would be a fun place to spend some time with toddlers - in July or August?

We would prefer a place that has free or cheap things to do - no Great Wolf Lodge type things.

So, help me search the map. Where can we meet and what can we do?