“I think you have a made a good point, but I feel… “
“I agree that x is y, but please consider my point that…”
“I respect what you are saying.”
“I have heard you out. Would you kindly allow me to speak without interruption?”
“I think we are getting off topic here. You have made a good point but x is a separate issue from what I am saying.”
...from my most recent post on Brainfodder.