I believe that a great par-three can only come about when several design features are combined. It's that old "sum of its parts" theory.
Length is not the deciding factor as the Postage Stamp & #7 at Pebble are both fabulous holes. Hazards such as water & bunkers may be great design features, but they aren't a necesiity in defining a hole's greatness.
For example, who doesn't think that 17 at Sawgrass with its island green isn't wonderful, but it only works because of the distance that it is played at. If the hole was 230 yards in length, what player, pro or otherwise, wouldn't be screaming, "Who's the idiot who designed this?" Yet if there were a landing area where someone could lay-up 160-180 yards left and short, and there were traps and land behind the hole, than a 230-yard carry into the winds and over the Pacific Ocean becomes possibly the world's most beautiful hole at Cypress Point.
The 10th hole at Winged Foot West is a wonderful par-three, yet if the USGA cuts it to a green speed of 13 for next years Open it will be unfair for many of the players and the potential hole locations will be severely limited. I use this as an example because many average players views of what are great par-threes are defined by what they see on television. In this case, I believe the hole's greatness can only be really experienced at a slower green speed when the cameras are not on.
When everyone thinks of the par-threes at Bethpage, that wonderfully photographic #17 with its oceans of sand comes first to mind, yet in all of my experience playing the course, it is the 8th hole that is usually the most difficult to get close to the pin on, yet there are just 3 features that cause this. On their own they each are insignificant if they didn't have the other two. There is a pond fronting the green that should never come into play, a bunker directly behind the left portion of the green, and a tree that has grown tall and lush and actually is ten yards short of the putting surface on the right and up the hillside of the green.
Not one of these would cause any problems if the other two features weren't there, yet together they create a target that makes the hole fabulous.
So, to make a long story short, I believe that a par-three's best chance at being great begins when the length of the hole is first decided on. It is only then that the architect can choose the proper combination of features that will bring it out.