Hello Teri,
You must be counting down the days to your cruise! I know I would be!
On my to-do list is sailing on the Disney Cruise Line (DCL). Disney just has so much to offer! So to help answer your question, I checked in with
Andi, the Disney Cruise Line Specialist on the Moms Panel. She and her family are actually sailing the Alaskan itinerary this summer.
While on your trip, temperatures can vary during the day from low 40s to upper 70s in the summer. So you might want to think in layers. I think you will have opportunities to wear shorts but there may be times you'll be happy you have lightweight pants or jeans too. Yes, more to pack, but I think it'll all be worth it!
For seven night cruises like yours, there is one formal and one semi-formal night. On formal night, jackets are required for men and dresses for women. It's not unusual to see some ladies wearing gowns. But some women wear pantsuits as well. On semi-formal night, think sport coats and shorter dresses. All the other nights are "cruise casual." With dining, always expect appropriate dress: no shorts, tanks or swimwear.
And if you don't want to bring formal wear on vacation, you can dine at Beach Blanket Buffet on Deck 9 which serves a sit-down dinner. Also, there's 24-hour room service on the ship. DCL thinks of everything!
I hope this helps! Happy sails!