Thought I'd take a shot at this thread.
Generally, there's not too many things I need to pack on a cruise that I wouldn't pack on a normal trip to Florida or WDW. There are, though, both formal nights and pirate nights. You can decide how formally you would like your family to dress up, and my family and I always get into pirate night with our pirate costumes (and we're always in good company
). Obviously swimsuits and warm weather wear are a must, and I would recommend at least some type of long pants or similar nice-ish attire for dinner (what you might consider "church clothes"). Otherwise, there's not much you need to pack besides that's not related to your Disney fandom. My family always brings magnetic signs that we put on our door, with our names, planned itineraries, favorite characters, etc. I'm also always sure to bring my pin collection. Any other Disney- or birthday-related items you'd like to bring are for you to decide.
As for Port Adventures... it's up to you, and everyone's different. It comes down to whether you like to plan vs improvise, pay to see a place vs take it in your own hands. My family usually will pay for excursions, depending on the port. Typically, if we're at a port and it isn't Castaway Cay or Nassau, than we'll pay for an excursion. Transportation is provided, so it removes the expense of a rental car; it takes away the risk of the cruise leaving if you're not back on board (since the cruise will wait for you if you're on an approved shore excursion); and it feels nice to let someone that knows or lives on the island take you around instead of having to figure it out for yourself. We LOVED the Mexican Riviera cruise for its shore excursions. If you're going to Costa Maya like we did, be sure to take a Port Adventure to see some nearby Mexican ruins. It's a very magical experience, and it's great to hear about them from a native of the area.
Just my advice. Have a nice cruise. :wave: I'm sure your daughter will love it.