Dh and I are babysitting 17m old B/G twins for our friends on Saturday from 10am-11pm. I've babysat them before, but not longer than 3 hours. I'd love some suggestions for crafts or activities to do at home and fun places to take a toddler.

Here is their schedule for the part of the day we will be there.
10:30am - parents leave
11:30am - lunch
12:30-1ish - down for a nap
2-3:00 - wake up
6:00pm - dinner
8:00pm - bath, books, bed

They have a playroom full of toys, but neither DH and I want to spend the entire day inside. We will have their car seats and stroller. I was thinking of bringing over a craft or activity to do with them in the morning to hopefully distract them from their parents leaving. Then when they wake up from their naps I thought that would be a good time to take them somewhere. Maybe the park and somewhere for a snack?

So my questions are what kind of crafts or activities are appropriate for their age and what types of places do you take your toddler?