[size=78%]I[/size] definitely do not want to feel exhausted, mentally or physically, at the end of a round.
To me, a well designed course has (a) a good "flow" to the round and (b) interesting greens.
Good flow needs a both a good routing and a variety of holes throughout the round. The variety I am looking for relates to both (i) challenges, (both in type of shots required and in level of difficulty) and (ii) hole footprints (e.g. lengths, elevations, directions, and straightness (vs doglegs) of the holes. However, all that variety has to fit together like pieces of a puzzle as opposed to feeling disjointed (like so many housing development courses). If in the middle of the round I'm thinking about how many holes do I have left to play, that's not a sign of good architecture. On courses that I think are well designed, it's more of a sense of "wow, we already played 18... I can't believe the round is over already". I do not want to feel beat up nor do I want to be bored. I like to replay a round in my head on a course I think is well designed and think about what I might do differently the next time around.