Grand Canyon
Derbent

Most popular un-visited: 1) Paris, banks of the Seine (sorry, I haven't yet crossed the Ocean)
Least popular visited: 937) Stone spheres of the Diquís (I've been for a while trying to cover my personally unexplored corners of my country, and that trip to Osa was my first attempt at doing that...from there on I have made some substantial non-WH-related travel)

Unvisited: Istanbul (currently nr. 18) and now i dont want to visit turkey anymore.
Visited: Gorham's Cave Complex this spring. The whole rock is amazing, but the cave? I dont know!

Paris #1
Ujung Kulon National Park #868

My "score":
- Statue of Liberty (#11)
- Virunga NP (#986)

Grand Canyon (26)
Bassari County (1011)

Rome (#4)
Tauric Chersonese (#936)

Highest not Seen (Going down to No 300)
146 Canal du Midi
229 Telc
237 Prambanan
255 Provins
258 Ksar of Ait ben Haddou
271 Bru na Boinne
285 My Son
Lowest Seen (From 970 up)
973 Nalanda
975 Takht-i Bahi
979 Al Hijr
980 Banc d'Arguin
993 Osun Osogbo
998 Gough and Inaccessible
1000 Aldabra
1018 Lope-Okanda

But the bigger question is how many of the "Highest not seen" and "Lowest not seen" are we ever likely to "pick up"!!
Highest Not seen
a. Can I really be bothered to go to France again for Provins and Canal du Midi when there are still many more worthwhile WHS still to see? They aren't even close together and neither really "attracts". No higher than "possibly" despite their closeness. Canal du Midi is more likely than Provins which only "scraped in" for its inscription.
b. Telc will (DV) be seen this Sept together with a tranche of other Cz/Sk/Pl/Hu WHS. It wouldn't otherwise be likely to get a visit!
c. Was last in Java in 1982 but we have 4 "not seen" WHS on the island including Prambanan. Mrs Solivagant has never been there and really needs to see Borobodur and nearby Bali. Also it is a good destination for European winter. So a "Probable"
d. Bru na Boinne is a "must do" and pretty easy on a short trip. So (DV) a "Definite"
e. My Son joins 3 others unseen in N Vietnam so it also could be a good "Revisit in European Winter" destination with our last visit to Vietnam being in 1994 – a "Possible"
f. The problem with Ksar of Ait ben Haddou is that I probably saw it in 1966 but am not entirely sure! Unlikely I think ever to go back to S Morocco for a 3rd time given other priorities so, I fear, that this (and Mazagan) will remain "unseen"!
Lowest Not seen
a. Might pick up "W National Park" if Benin ever gets its extension as have visited its T List part of the transnational park.
b. It is "possible" we might re-visit Senegal to pick up its 5 missing sites including Bassari Country. But our previous 2 visits to the country were not particularly wonderful and Bassari sounds a bit of a hell hole for tourists now so we will probably be happy that we saw a fair number of African CLs such as Koutoumakkou some years ago and give it a miss!
c. We are unlikely I think ever to visit any of the other unvisited sites from 970 up - either not interesting enough to us, have already visited enough of the country/similar sites or too costly - so none of them are "targets"!

Is anyone else prepared to say "I really can't be bothered to see this WHS, unless I happen to be passing for other reasons" - or is everyone still "gung ho" for trying to see them all or as many as possible, whatever their interest/quality??

Not sure why Provins always gets such a bad reputation. It's really nice. But that's just me. Canal du Midi you may have ticked off already if you have been to either Toulouse or Carcassone.

Interestingly, I have 4/7 covered even though you have seen way more than I ever have (or will). But those are all in Europe, so they are easy ;)

Florence (maybe this year)
Los Katios (it seems that so far I am the only WHS enthusiast that was there)

Not so much a "bad reputation" but a reputation not good enough to make it a "destination"! If one has a spare day in Paris some time or if one finds oneself motoring east of that city then - certainly one would take it in. The word "nice" in English is regarded as a rather minimal compliment ("Damning with faint praise"!). Even Michelin, that "gold standard" French cultural guide book, only accords it 1 star (= Worth a visit if you are passing) and there are many such towns in France.

It was actually rejected and withdrawn in 1998 but, as the 2001 AB evaluation states (without explaining how) - "In the present proposal, the nomination has been revised completely". I quote below from the minutes of the 2001 WHC on the subject of its inscription
"The Delegate of Greece recalled her intervention made at the twenty- fifth session of the Bureau in June 2001, underlining that nothing remained of the installations relating to the Trade Fair in the Medieval Town of Provins, while other cities preserved better examples.
Several delegates questioned the research carried out on medieval fair towns, and asked whether archaeological excavations had taken place at Provins. The Delegate of St Lucia requested the reasons for the change in the recommendation by ICOMOS from negative in 1996 to positive in 2001."
I think France "got away with" this one!!!

Not yet! But I am not in a hurry to tick off for example my last 3 remaining Czech WHS, and would not plan a holiday around it.

From the costly ones at the bottom of the list I have my eyes set on Sangha Trinational and the two sites in Chad in the coming 2-3 years.

Yeah fair enough, they include the two last ones that I picked up as well, hardly world beaters.

I have a soft spot for Litomysyl, but that is just because I had a lovely day there. Lednice- Valtice can be picked up easily if you ever find yourself in Vienna, and probably the most interesting thing about Kroměříž is the mangled attempts at trying to pronounce it, I doubt I have ever said it the same way twice.

Highest unseen: Venice (#5), and Florence (#7). I've seen everything else in the top 20, but an embarrassingly small amount of Italy!
Lowest seen: Antequera Dolmens (#726). I suspect it's only so low down because it's a relatively fresh addition to the list.

Unvisited: Tower of London (#2) - despite the fact that I travel to London on a regular basis (eg. last Tuesday on a business trip) I somehow never bothered (yet). I guess it's one of those places where I'm just thinking "I can go there anytime".
Visited: well, extraodinarily, since today (or better: at this exact moment), it seems to be Gulangyu/Kulangsu (#1044) - though this is certainly related to the fact that people haven't updated their visits count yet. Discounting this year's sites, it would be Sites of Japan's Meiji Industrial Revolution (#759).