For me it has always been the theme from Pirates of the Caribbean. It first started when we went to WDW and stayed in a theme park view room where the music to the fireworks was piped in every night. We loved the Pirates section of that fireworks show. Then the following year, our first Pirates in the Caribbean party was on the Dream where that theme was played again (B2B so we saw the show twice, LOL). After those two trips, that theme always reminds me of cruising/vacations (even though most of my cruises have been on the Wonder and they don't use that song in those fireworks shows).