I am taking my nieces and their friend (ages 16, 13, and 13) on the Explorer July 28. Any suggestions or tips would be appreciated, i.e., as in which shore excursions would you recommend, what are some on-board activities that should not be missed, etc. What type of clothing do they need to bring (are they expected to dress up for formal nights?) Also, anyone else with teens cruising that date? Thank you!