Both ね and でしょう can be used to form tag questions to confirm an opinion like so:
1) 疲れたでしょう。 (more of a guess based on evidence / polite)
2) 疲れたね。 (more forceful / the speaker is more certain)
3) 疲れたでしょうね。 (forceful, but polite)
For the purposes of these questions you can imagine that these sentences are spoken to someone who has just done something physically exerting (like moving boxes for 7 hours).
Am I right about these guesses? Can anyone elaborate more?