Hi Sonia!
How exciting, a first visit for the kids and your first in over 10 years...this will definitely be a memorable trip!
Each of the parks has attractions geared towards little ones. My first pick is Magic Kingdom, because not only is it easy to see the abundance of attractions that little ones can experience, but it is, in my opinion, the most magical park. Hollywood Studios, Epcot, and Animal Kingdom, have great attraction, too. Consider the interests of your children, and then check out
this page which has park maps in a pdf on the right menu which highlight attractions geared towards little ones. There's also a pdf listing attraction height requirements at all of the Disney parks. (If you notice an attraction is not listed, it can be experienced by a guest of any height.)
Character dinners are a fun way to slow down, but still take in some of the Disney magic. My kids used character dining as an opportunity to warm up to the characters when they were still shy about meeting them. They were able to see the characters walking around the restaurant, interacting with other families as they approached each table, and when it was their turn they were ready for hugs and high fives, as well as smiles for the camera.
A few of my favorite Character dining locations include Chef Mickey's, The Crystal Palace (featuring Winnie the Pooh characters), and 1900 Park Fare (featuring Cinderella and others in a Happily Ever After dinner). While I haven't yet attended, I've heard great things about and even have reservations for Mickey's Backyard BBQ. There are more great dining places that feature characters for breakfast and lunch, let me know if you'd like me to share them with you!
Hope this helps. Have a magical vacation!