Having family from that area I can give you plenty of places to go. First, do check out the Lancaster County web site that will give you general information about the area.
Now for the girls you can go to Dutch Wonderland and Hershey Park you can buy a combination pass that will allow you to have passes for both parks at one price to me this is a great deal. Also Chocolate World is right at Hershey Park and you all will enjoy it.
The Starsburg Railroad is another great attraction for the children it's a wonderful train ride through the country but, have to warn you if it's planting season be prepared for the wonderful smell of fertilizer in the air. My wife just loves that smell

. They will also stop the train and tell the story of the ghost train and you can hear the whistle from the ghost train too

As for restaurants there are so many to choose from, on route 896 there is Good and Plenty this is an all you can eat style restaurant but you are seated with other folks from different states and the food is all Lancaster County food it is served family style which means it keeps coming until you can't eat no more and desert is the same as well.
On Route 340 there is Bird in Hand restaurant this is another well kept secret in Lancaster County they have an all you can eat buffet or a very good menu to chse from too. We always will go here when we are in town it is just a great family restaurant.
Last but not least is Millers Smorgasbord, this is where you can eat and eat and eat!! It is a little pricey but for the food you get it is well worth the price and you never feel rushed to eat as in some places.
There are too many places to stay to really tell you which one to pick we have stayed at the Country Inn and Suites which is directly across from Dutch Wonderland it is a very nice hotel which serves and quick breakfast every day but it can be expensive.
Just do some research for the hotels and I'm sure whichever hotel you pick you won't be disappointed.
Have a great time...