I've been to only two you haven't. Brazil and Ireland. One of those should be easy enough. First weekend of May and June are usually good. In the other direction, the list is long.
Ireland and Scotland are on the "to-do-list". Especially The Cork and Kerry mountains.
Not sure did you ever cross paths with Seppo who I mention at the bottom of the post. He's a bit older than I am but he has 106 countries. I almost quit my collecting at that point.