"The Savage Curtain" does, paraphrasing, start with "This is our last orbit" and end with Let's go to our next assignment, could have been worked bittersweetly with it actually being the finale but just a little too much to have Abraham Lincoln (!) and Kahless and/or Surak in finale, with being that big, especially with starting with Lincoln being huge in space, I think works better as near the end but not actual last episode.
"The Tholian Web" Kirk apparently, seemingly dying and the crew taking seriously that they'll have to move on without him (even though we know they actually won't have to) kind of works for finale but I think better for midway through last season.