Hi Deborah,
I know you're super excited for your first trip to Disney World and I'm super excited for you! What a great place to visit for Valentine's Day. I heart that idea.
Disney's Spirit of Aloha Show is awesome fun! The dress code is casual and shorts are permitted. My boys usually wear khaki shorts and their Hawaiian Disney shirts. I usually wear some sort of casual matching outfit. It does seem that while its casual, most Guests freshen up and change if they've been in a theme park all day.
Keep in mind that while the theatre is covered, it is open air so if its a little chilly during the evening, it will be chilly during the show. I'd recommend checking the 10-day forecast on
www.weather.com a couple of days before your trip. That will help you decide if you need a light jacket or wear long pants to the show. Also keep in mind that the show may be cancelled due to inclement weather.
Enjoy your first trip to Disney World - you're going to love it!
Wishing you many magical memories :-) Allison