That being "nice" gets exhausting at times, and a completely honest expression of one's feelings would probably end up being put in the "asshole" category.
I want to pick from this particular line of yours above, yes being is nice is great and most time we are nice because we want people to be nice to us in return, but the honest truth is that expecting the niceness in return might not be the smartest thing because we might end up not getting it back.
It's either we go ahead and be nice and expect less or sometimes we just do what pleases us and forget about what people will say. I have being so nice couple of times and I never got it back in return, sad but true. Thanks for sharing this great blog of wisdom which comes with somuch lessons.