The Right to not be Offended I think the right to be, and not be, offended is an important part of political and social discourse. However I don't think it should be a criminal offence if you do offend someone.
Not matter what you say, someone somewhere may be offended. It is completely outside the control of a speaker to prevent this. For example: even if a speaker was to tone down their language in order to placate the dissenters of his/her opinion, the fact that he/she is "sugarcoating" his/her speech can upset the people that wanted to hear him/her speak in the first place. No matter what you say, someone will take offence.
So I don't think it is fair to hold a person accountable if he/she offends someone.
However it is important for members of a society to express themselves when they take offence. This process, I believe, helps a society at large determine whether an idea is "good" or not and build a moral system that can be agreed upon. I see offence as a mechanism people can use to show their disapproval regardless of how eloquent they are and if lots of people are finding a particular idea offensive, we, as a society, have a duty to explore why. Of course, this only works if there is no capital punishment for offending someone; an idea that is offensive is not inherently wrong, and radical, progressive ideas tend to offend a large number of the populous. In this case, it is the responsibility of the speaker to be eloquent enough to convince people not to be offended.
Lastly, I also support the right to not be offended. Personally, someone will find it very, very difficult to offend me with words alone. For example: I'm black and therefore I have been called some interesting and creative racial slurs. I have never been bothered by this and racism has never negatively affected my life. I actually encourage my partners to call me a N****r to desensitize them from the word and prevent them from being offended on my behalf. Which brings me to my point. People should have the right to not be offended so people like me, who just want to get on with life, do not have to worry about our lives being affected by people who are being offended on our behalf. Without the right to not be offended, I feel this could not happen and will cause even more political and social divisiveness then the people that espouse socially objectionable ideas.
Sorry, rambled a bit there.....