The longest one I'd thought of from the top of my head was "Newcastle - Eldon Square Bus Station",
but out of the stops on the 65, I think "Buckinghamshire Road - Nottinghamshire Road" would be the longest stop name.

I had "Washington District 15 Exit" on the route of the 8 in mind at first, but that's definitely not the longest stop name!

Outside of the north east, I wonder if next stop announcements for buses going through Llanfairpwllgwyngyll simply say "Llanfairpwllgwyngyll" or if they use the full name, i.e. Llanfair­pwllgwyngyll­gogery­chwyrn­drobwll­llan­tysilio­gogo­goch.