Hi Robin,
You didn't say how many days you are coming for, but if you have a Magic Your Way ticket with several days on it, but not 10, then adding another day is very
inexpensive; if you already have a 10 day ticket, you can not add any more days. Personally I would only plan on going to a park if it is staying open late or if it has evening Extra Magic Hours.
If you do not want to do that then there are plenty of additional things you can do outside of the parks. My family especially enjoys visiting
Downtown Disney even if we are not shopping. There are plenty of great family restaurants there. If you're looking to save money on food there, then I highly recommend Earl of Sandwich which has great food and is reasonably priced. The LEGO Imagination Center has a free play area filled with lots of blocks for your family to enjoy! Young children usually enjoy the interactive fountains there as long as they don't mind getting wet.
Another idea is to visit
Disney's Boardwalk. It is built around a lake and the theming is fabulous! It's especially wonderful at night so this could be perfect for you. There were often street performers, such as jugglers and comedians, when my family visited. Your family can also try some carnival-style games, though there is a small cost for that. The Atlantic Dance Hall is also located there.
Touring the different Disney resort hotels is also a fun thing to do. My children especially enjoy visiting the Animal Kingdom Lodge and looking at the animals on the savannah. If you are visiting during the holidays, touring the resorts is especially enjoyable as their decorations are amazing.
Have a great vacation and write back if you have any more questions!