Hi, Patty! What lucky grandkids you have! They must be so excited to be going to WDW with you and Grandpa!
Let's start with Simbas Clubhouse. While my kids have never used Simba's, I have read great reviews of it. To make reservations for Simba's Clubhouse, call (407)WDW-DINE and their direct number is (407)938-4785. This facility is for children ages 4 - 12, and the cost is about $11.25 per hour, subject to change. Hours are 4:30 p.m. - midnight. Cast members will give you exact hours and pricing when you call.
While your grandchildren are having a wonderful time exploring Simba's Clubhouse, you and your husband can head over to
Boma in the Animal Kingdom Lodge. I really recommend reservations. This is a very popular dining experience and it will be much easier to have a table waiting for you after the kids are dropped off. Since your wait staff will be clearing your plates and bringing your beverages, you do still tip even though it is a buffet. I usually tip around 15% - 18% at a buffet and 20% at standard table service restaurants.
You can make reservations for Boma at the same time you are calling to reserve a spot at Simba's Clubhouse by calling (407)WDW-DINE. You are less than a month out from your vacation, so call soon as reservations do fill up quickly.
Wishing your family a magical vacation!