Should there be a separate poll for the National Wonders? Especially given that we're out of poll slots.
I've been to 5-7 of the Global Wonders. Depends on how you count "visit" for a couple. Does seeing the wonder count or do you have to actually step inside (if applicable)? Does "Wall Street" mean seeing Wall Street (the street itself), or the district, or the
Charging Bull statue, which is actually on Broadway (and if you've seen it, have you seen Broadway?).
Three of those seven have been somewhat incidental. Hollywood? I was there on a work trip, cool to see (the sign and the tourist area), probably won't return. The Pentagon? I flew into Reagan National (
they do offer tours). Statue of Liberty? Depends on whether you can see it or have to take the tour, but I happened to wind up in Battery Park, and there it was across the water; I don't feel like I missed out by not spending my day going on the tour.
Least worth visiting? Versailles. At least when I have been there, it was way too crowded to be enjoyable. Maybe it's good on a weekday in the off season, but if I go back to France, I'll go to a less-well-known castle somewhere else instead. I much preferred Hampton Court Palace in England, which wasn't quite as ostentatious, but was also not packed.
Least common one I've seen? Stonehenge. You can't get as close to it as you might think due to fencing, so you don't really get the full-scale experience, which was somewhat disappointing. On the other hand, you can get up close at Carhenge in Nebraska, which may not have been accumulating culture for thousands of years, but fully met my expectations when I visited. Both are rather far out of the way for most itineraries, but Stonehenge is at least close to Bath.
I'm not sure how many more I'll see. These days, I increasingly plan my travel around the outdoors, and even before that, had preferred to avoid the most-popular tourist areas for some time, due to crowds and/or lines.