Does the time someone whispered "Want to go upstairs?" in my ear count?

Other than that, I'd have to say Paris. That would be a combination of the place and who I was with. We weren't married at the time, but we are now (and have been back since for a return visit).

In terms of the place itself, Hawai'i and Australia are right up there too, but there are so many different aspects of "best." The best scenery? The best food? The best people? The best activities? It could be a long list!