Both attractions can fill an entire day, especially with a little one. Storyland in particular has lots of activities, not just rides. It is designed with little ones in mind. I found that it was easier to just take your time and and not try to cram too much into one day when our son was young. Suggest checking the websites for both places and see what would interest your 5 yr old and plan accordingly.
For a 5 yr old, there is always a good motel with a quiet pool and a little playground. I always liked the Willey Slide park out in Crawford Notch for a stop. There is a pond with ducks for the kids to feed, picnic tables and places to walk.
In North Conway, there is a Friendly's restaurant for an ice cream stop too.