sensible way. That bridge in Switzerland would probably be tagged with "Ginevra", "holiday", "aunt", and "Isabel" (plus a few prepositions).
You cannot be serious!?!
Theoretically tagging is a great system but in the hands of a gazillion amateurs it will most likely lead to missing images, not found ones.
Yeah, and a Wiki doesn't work in theory either, fortunately it works in practice. Have a little more faith in our users. We don't have any "Holiday" or "Aunt Isabell" categories either. Claiming this will change when we use categories as tags is completely unfounded speculation (or FUD).