OK,
Thought I'd think this through. Countries I've visited are:
Britain,
Ireland,
France,
Spain,
Portugal,
Belgium,
Luxembourg,
Netherlands,
Germany,
Austria,
Switzerland,
Italy,
Denmark,
Sweden,
Norway,
Greece,
Czech Republic
Croatia (it was still Yugoslavia at the time)
Slovenia (also still Yugoslavia at the time)
Egypt,
Tunisia,
Morocco,
South Africa,
USA,
Canada,
Mexico,
New Zealand,
Mauritius
United Arab Emirates.
Of those, I've live in the UK, the USA and Germany (albeit for only six months).
I definitely need to start seeing more of Asia. A visit to South America is also overdue.
If I absolutely had to move from the US, to a country I've already been too, it would be Northern Italy. Great people, great cities, the Alps, the Lakes and the Med all within easy driving distance.