For tropical places, I liked Hawaii (scuba, snorkeling, jet skiing, parasailing, rainforest death march after meeting a guide at the top of Diamond Head etc... etc...) and San Juan, Puerto Rico (similar to Hawaii, but add in swimming in bioluminescence at night after jumping in a stranger's van to meet Captain Suarez).
Oh Hai. I wish I had photoshop/and could photoshop a shark lurking the background.
Of the places I've been though, I think I liked Paris (obv things like the Eiffel Tower, Champs Elysee, Arc de Triomphe, Louvre, Notre Dame, and Montmartre) or Venice the best. The Vatican was cool, but it was pretty crazy when I was there as I ended up there on Easter about 8 years ago (probably one of the only Jews).