Jenny, I hope you are getting so excited for your trip to Bay Lake Tower at Disney's Contemporary Resort! I'm so jealous!
First, you'll see the time for roasting marshmallows listed under the Campfire on the Beach on the Activities sheet you'll receive at check-in. (So cool!) Regarding a quick / relaxing option for food for your arrival day, we really enjoy the variety and convenience of options from
Contempo Cafe. On a day where we just need to relax at the resort (such as check-in day), one of the adults can grab food for all of us and tote it back to the room very easily in large, handled paper bags. The other adult stays with the kids in the room to unpack. I suggest that you take a look at the online menu so that you can be better informed of your options before that one adult heads out to pick up food. We've really enjoyed everything we've ordered from Contempo Cafe, and the bakery items they have there are wonderful, too! There is plenty of seating, also, should you wish to eat right there.
Of course, the other locations you've mentioned each have their strong-point and signature item(s), too, but they will each require you to hop onto the monorail to enjoy them, which isn't nearly as relaxing as ordering right there at your resort. Top of the World Lounge is right there as well, and is very relaxing (with a
fabulous view!) so if your little ones are flexible, that would also be a nice place to order a beverage and a snack. Consider a QS dinner at Contempo, followed by a campfire at dusk, then munchies and beverages at Top of the World. What a way to start your vacation, Jenny...might be hard to beat the rest of the days there!
Keep those questions coming, Jenny. We are all so happy to help!