I'm really glad that these past two seasons they did some countries that were undervisited. I really hope that they do more of Korea since there's so much there and you can get direct flights to and from all around the US, so it would be good starts/finales. Would love to see Busan when they go back, or if they go back to Seoul that they also do Incheon. I would also really love a double leg here.
I think in general they need to visit more locales that haven't been visited. For example, they keep visiting Tokyo and Osaka in Japan, when they could visit Sapporo, Okinawa, Fukuoka, etc. China too, I wish they'd stop overusing the big cities and visit Chongqing or Qingdao, both of which have nonstops to the US. Also think they should visit Lhasa and Urumqi. With Indonesia, I'd like to see Indonesian Borneo, Sumatra, and Indonesian Papua. I'm really glad they went to Chiang Mai this season and stepped away from Bangkok and Phuket, they need to do that more. With Vietnam, I'd love to see Hoi An, Da Nang, Phu Quoc, Sapa, or Nha Trang. I hope when they revisit Taiwan that they go to Kaohsiung, an absolutely beautiful season. In Cambodia, I'll say this: everyone here wants a revisit to Siem Reap, but having just visited Siem Reap, there's really not much to do there outside of Angkor Wat, which they've already visited. I guess they could do something on the Pub Street and then head in the morning to Sihanoukville. Philippines needs to be visited more, would like to see a visit to Cebu. Mongolia is long overdue, but I understand due to costs of getting to Mongolia, it's very difficult.
Moving away from that part of Asia—India, they really need to visit Goa, Bengaluru, Pune, Hyderabad, the Indian Himalayas, and so much more. Come on with Nepal! Even Phil says he wants it. Next time they go to Bangladesh, they should mix it up a bit and go to Chittagong. Maldives would be a great pseudo-South Central Asia leg. I'd like to see more Abu Dhabi and less Dubai, and maybe visits to Sharjah, or a quick dip into Oman's Mussandam region (only a few hour drive from Dubai). Glad that they went to Bahrain, but would also like to see Jordan, Lebanon and Qatar. I would LOVE a visit to Iraqi Kurdistan (it's actually very safe and easy to visit). I hope they do more Central Asia, like Kyrgyzstan, Tajikistan, Uzbekistan, etc. I think they need to step away from Istanbul in Turkey and go visit Cappadochia.
I think a return to Egypt is overdue, maybe this time go to Hurghada, Sharm el-Sheikh, Aswan or Alexandria (I'd also really love for them to visit Abu Simbel). Ethiopia is long overdue. Kenya needs a redo, and I don't know why they haven't visited it for an actual leg. We can all agree on South Africa. Zimbabwe was nice, but that was twice within four seasons, and I'd rather see countries that haven't been visited yet or at least in a long time. Cote d'Ivoire and Togo are great ideas to visit. I'm really glad that the visits to Morocco have mostly been diverse, but would love to see Rabat or Casablanca, although I think we need more time before visiting Morocco again. Tunisia is due for a revisit, they could visit Carthage and do Carthaginian Tasks while there. A final leg in Cape Verde would be great, as there are flights to Boston, or even if it was earlier, they could fly to Brazil.
Now Europe. Eastern Europe is undervisited. Everywhere. I'm glad every time they've done Greece they've stepped away for Athens for part of the leg, but would also like to see Thessaloniki and the Greek Islands. I hope when they return to Romania they do an actual leg in Bucharest or maybe something new like Cluj-Napoca. Russia needs less Moscow (maybe a visit to Vladivostok?). Germany needs less Munich, more Frankfurt, Cologne, Baden-Baden, Nuremberg, Dusseldorf, etc. They've been pretty good about mixing Italy up. France too, although I'd like to see a visit to Strasbourg, Montpellier, Lyon or Marseille—they could do a leg where they start in Basel, Switzerland and then end in Strasbourg. We need less London. Spain has been pretty diverse, nothing is really overvisited, and I'm overall surprised we haven't seen Madrid, but I'd like to see Ibiza and Alicante.
South America—less Brazil, Argentina, and Chile. More visits to everywhere else in South America. Would like to see Suriname. Not much more to say, considering they mostly just visit Brazil, Argentina and Chile EGGPLANT(although a visit to Recife in Brazil would be a nice change of pace).
Central/North America—honestly not too unhappy, but maybe it's because I'm American and it's all close to home. If they do Mexico, they should stay away from Mexico City and Cancun.
Oceania—just overall more. Stay away from Sydney. Would love to see Fiji (one of my favorite countries I've been to), Tonga, Palau, and Vanuatu. Go back to Perth, a new visit to Melbourne (hi Bourkie!), Tasmania, some Great Barrier Reef since it's dying, etc. Papua New Guinea would be cool, but it's pretty dangerous, so probably not happening.