You may want to go and talk with the counslers and see if they will put your girls together, it never hurts to ask. As for the tipping, just follow the guidelines in the brochure, its $3.50 a day, per person for the cabin attendant and the dinning room waiter, and $2.00 for the assistant waiter, you may want to add something to the head waiter if he should do something special for you, thats up to you. They will give you envelopes the last full day and you can leave the cabin stewart his/hers when you leave for dinner and bring the rest of the envelopes with you for the dinning room staff.
We've alwasy tipped the same amount for the kids, the staff seems to go out of their way to keep them happy and they deserve the tip, they almost do more work when it comes to kids too.
As for excersions, depending on if your kids are old enough, I'd suggest sting ray city in Grand Cayman, a great time and Dunns Rivers Falls in Jamaica.
Having cruised on Explorer, there is so much to do onboard, just check your daily compass and see what activities they will have for the next day. Definately see the ice show and the girls will love the parades, at least 2 during the week.
Here is a link to some great first time cruiser information, great tips:
Have a great time!
Tuesday Chat Host