CJean, the roads in Namibia are comparatively decent. It is one of the easiest places to travel, because
-The roads aren't terrible (but don't travel on them at night, because of the risk of hitting an animal).
-English is the official language, although it is not necessarily the most commonly spoken language. Nevertheless, signs, menus, and people in the tourism industry all use some English.
-The water is mostly safe to drink.
-Malaria is limited to a few areas, and is even less common in their winter (our summer).
-The government is pretty stable.
In answer to the OP...no, I couldn't just throw a dart at a map and go, but my comfort zone seems to be a lot larger than that of many posters in the "anti-bucket list" thread. For instance, Africa is a HUGE continent--much, much larger than the Mercator maps make it seem. There is no way I would completely rule out an entire continent (well, except maybe Antarctica). Now, having been to Namibia--probably one of the easiest and safest African countries in which to travel, there are others I am definitely interested in travelling to, especially Botswana and Uganda or Rwanda (the latter two to see mountain gorillas). Also, I know someone from Morocco, and she makes it sound so wonderful, I would like to visit there someday.
Some people in the other thread mentioned South America. Again, while there might be certain areas I'd steer clear of, it's a big continent with different countries on it. I've already been to Ecuador and Peru (although I wouldn't go to Peru right at the moment). I'd like to go to Colombia. My daughter-in-law is from there, and she and my son have travelled there many times--in fact, they just returned from a trip a week ago. They even lived there together for 6 months while my son did a semester at university there, and my d-i-l worked on her Master's thesis. Then there's Brazil. My cousin's daughter did a year abroad there, and it seems like a beautiful country.
My very first trip outside of North America--15 years ago now--was to Hong Kong, Macau, Tokyo, and Kamakura. Macau, Tokyo, and Kamakura had very little English, and DH and I didn't have smartphones or GPS at that time. Since that experience, I find navigating countries with Germanic or Latin-based languages very easy (especially as I know some French).
So, language, culture, distance, etc. are not deterrents for me, at all.
If I felt there was some likelihood that my personal safety was at risk, beyond the usual precautions against theft, problematic drinking water, etc. I might take, then that would be outside of my comfort zone. So, I wouldn't go to countries where war or riots were commonly happening, for example.
The other factor is literal comfort. I don't do camping. I will rule out staying in places where the accommodations would be very rustic or exposed to the elements. So, for instance, we didn't do the long hike to Machu Picchu. It wasn't the hiking; it was the idea of having to camp overnight that deterred me. So, my comfort zone involves a real bed, doors, and some access to running water.