I think these countries are due for a revisit (after two seasons of Africa they might skip it this season)
-North America-
Mexico (despite Travel Warnings, there are safe places like Cancun)
Canada (Vancouver or Montreal)
Costa Rica (Panama was revisted, why not Costa Rica)
-South America-
Brazil (They need to visit the inland cities like Manaus, Brasilia, or Belo Horizonte)
Peru (They been to Cusco on TAR7 but failed to visit Machu Pichu, which was nearby)
Bolivia (Lake Titicaca or Santa Cruz)
-Europe-
Iceland (Since TAR6 I like to see a leg in the capital city of Reykjavik)
Scotland (Loch Ness or Edinburgh)
France (French Riviera cities of Nice/Cannes or Lyon)
Spain (Madrid or Valencia)
Portugal (Lisbon again)
Greece (despite the economic crisis there, the Greek Islands like Crete, Santorini, or Paro)
Finland (a whole leg with a pit stop in Helsinki or Finnish Lapland)
Turkey (Izmir or Anatyla)
-Asia-
China (Hainan Island, Guangzhou, Macau, Xian, or Sichuan)
Philippines (The safety of Palawan Province or Laoag City)
Indonesia (A leg in Jakarta or Bali)
Thailand (Enough of Bangkok and Phuket, how about some Chiang Mai and the north)
Vietnam (Central Vietnam since TAR3)
Russia/Siberia (Irkutsk/Lake Baikal or Vladivostok)
Malaysia (Kota Kinabalu or Kuching)
-Oceania-
New Zealand (Wellington or Queenstown)
Australia (The true Outback like Alice Springs, Ayers Rock, or return to Coober Pedy)