Need an outing idea

JenRose9/24

Next week I am babysitting my niece and nephew.  My nephew will be in school from 7:30 until 4 each day.  I took off work so I could take my niece and son somewhere fun.  They are both 2 years old and very high energy children.  I thought about somewhere with inflatables but then questioned whether I could handle both of them in a setting like that - what happens when they bolt in opposite directions?  Or if I have to help them climb the steps to the slide I'm not sure I could handle both of them.

 I have a double stroller so I am leaning toward an activity that keeps them confined for a good portion of the field trip. 

We don't have an aquarium close unfortunatley.  I haven't been to the science center in years so I don't know what they have that is age appropriate for a two year old.  What ideas do you have for me?