Well I don't see Jamaica or Caribbean on the list?
Otherwise London is a major size city and cannot be covered in a short time, you should return and enjoy some city life while you are both under 30 after this age the appeal seems to change as do the crowds you will be accepted within.
Also revisit Canada it's kind to people is so vast there is probably loads that you have missed!
Would make very interesting research for an author, although in your other post you claimed to be an accountant?
Experienced travellers are abandoning the "where" or travel for the "how". It is called experimental tourism. Like the guy who travelled around Tokyo in a bear suit or couples who go to a city then they try and find each other somewhere in the city.
I am not so adventurous, but I like to do things like... In China there are 5 Taoist mountains and 4 (or 3 depending on how you count) buddhist mountains. Have you walked to the top of all of them?
Another one would be to volunteer in a place, learn a bit of the language, help little kids in Vietnam, train elephants in Thailand, watch whales in Australia. Something like that.
Or how about going to a random city, renting a nice big pad, then going up to random people an inviting them a cool party.
PS: I noticed you have done the south east pacific islands...but maybe you just left it off.
Now a this time you can visit Austria because that country is also most of places are Beautiful for visiting. There is no pollution and city also need and tidy.
If you were gone this much, how did you ever manage enough money to pay your bills? If you're self-employed you cannot leave your business to chance and to strangers. This just sounds so implausible. Believe you're a troll.