Hi Michael Woods, welcome to Cruise-Chat! Congratulations on your up-coming cruise! The Grand Princess is a grand lady. I hope you enjoy Princess as much as we do. They're our favorite line, so far.
We haven't used the soft drink package because you'd have to drink a lot of soda to break even, which we don't. They have coffee, tea, juice, milk, and punch for free. So, if you don't drink that much soda, it might be less expensive to just purchase a can or two. If you do drink a lot of soda, then the sticker is well worth it.
We have done the wine package. It depends on the type of wine (premium, standard) you purchase as to the price. They also have a bar set up you can purchase for your cabin.
Princess has a children's club, which I think your children would enjoy. They do all types of activities, treasure hunts, cook outs, arts and crafts, games, sleep overs, etc. Most of the children would rather do the club activities than hang with their parents, but I'm not sure about your children. There is a video arcade on board for them, too. It can get expensive, so let your children know what their limit is.
There are some great activities for adults as well. The Sanctuary is for adults only. It's $10/pp for a half day or you can purchase a package at the beginning of the cruise for unlimited usage.
The Movies Under the Stars will be great for family time. They show relatively new movies and give you blankets and popcorn. The movies playing will be listed in your Princess Patter (newsletter) that will be in your cabin daily.
Best wishes for a marvelous cruise!