The "agree to disagree" thing is at best condescending, at worst a desperate way to escape a thorough discussion where you're pretty sure you're going to "lose" i.e. have to face an uncomfortable truth to begin with.
"I'm sorry you feel that way" is a cop out and a non-excuse. It makes the sender feel better and the receiver feel worse.
Well, I'm sorry that you feel that way.
It seems that we have a differing opinion on the subject but I still value your opinion and we are still friends.
See how that works? I still think I am right, you still think you are right. I wish I could bring you over to my side but it seems that I can not so I regret your feelings. Then I told you so, (olive branch).
Good talk bro. :)
:) let's see.