Sean,
Here's an interesting example of how par affects a golfer's thinking:
The 13th hole at my home course (Essex G&CC, D. Ross, 1929) is currently a 471-yard par-5.
Currently most average golfers at the club (I'd say, 10 handicap and above) simply play this hole as a three-shotter to the green. There's talk of calling this hole a par-4. If this happens, all of a sudden, many of the same golfers -- who shouldn't change their current strategy -- will undoubtedly begin to think they need to reach the green with two shots, because it's called "par-4".
Terminology immediately makes the hole more difficult for these (psyched-out) golfers because they'll be trying for the green with their second shots... the putting surface here is angled and significantly elevated, surrounded by difficult rough, and there's water and bunkers nearby.
Good players, on the other hand, typically play a long-to- mid iron to the green at the 13th hole. With regard to strategy, this hole remains the same for low-handicappers (long hitters), no matter what you call it.