I'm writing a short text and I got stuck because I wanted to write that my parents, who are now at home not working seeing that they retired from work, seem to be unhappy. Can I say something like: 両親は働かないで嬉しくなさそうです?
I'm gonna say, "両親は定年になってからというもの、毎日つまらなさそうにしています．"
It literally means "Ever since my parents retired from their work, they look miserable."
Or respecting your original words, I would revise as "両親は働いていないので、楽しくなさそうです."
Hope it helps.
I would use 〜みたいです。みたい can be used to express your opinion or assumption based on what you have seen first hand. “It looks like”/ “It seems like”. そう I believe is more commonly used for things you've heard.