Ed,
I don't think you can make the blanket statement that you have to play the "best" courses when going somewhere. I think it depends on who you are going with, whether you think you will be back and cost. For example, I was in Scotland for 9 days last August, and I didn't play Prestwick, Troon, Turnberry, Dornoch, TOC or North Berwick.
However, I did play 18 rounds of golf over there and I don't regret the fact that I didn't play the "worldbeaters." (I did manage to play Western Gailes, Cruden Bay, Royal Aberdeen, Murcar, Kingsbarns, Elie, Carnoustie, Loch Lomond, etc.) I decided that the trip clearly wasn't going to be my last, so my friend and I decided to play courses that were a little more off the beaten path. I view Prestwick, Troon, Turnberry, TOC, Muirfield as "easy" to play. You just have to be prepared to drop lots of cash. We decided that since it was just the two of us, we would play courses that we wouldn't be able to get a big group of golfers interested in playing.