^ I would have probably said "yeah it's beautiful" or "sure is!" and keep on my way. Sure I'm not really serious, I'm just saying the nicest thing I can that will also prevent the conversation from progressing.
Deus Ex Lemur, you said "Thoughts I get that never would enter their heads, or for minimal time. They may have their own issues but I know it's not like SA or extent of mine." I feel the same way, when I'm talking and looking at them and they're really into whatever they're saying, talking loud, and I'm thinking about things like "is this real right now?" and "this is weird, man. Everything is weird." you know, weird philosophical thoughts about people, their eyes and expressions.