Nothing better than putting for eagle on a par-4! I think that happened to me once...
I think my favorite is the 17th at Oakmont. I've played it about 30 times, went for the green each time, drove it on the putting surface exactly once, whiffed an 8-foot eagle putt but made my birdie, which didn't make up for the bogey or worse I made every other time I played it!
Many of my other favorites are in the UK and Ireland:
8 at Cruden Bay
2 at Muirfield
13 at North Berwick (The Pit!)
16 at Prestwick (really just a long par 3 over the Cardinal Bunker!)
10 at Elie (completely blind, hit my driver over the green into the Firth of Forth!)
4 at Crail (driveable over a corner of the North Sea)
1 at Royal Dornoch
8 on the new Kintyre Course at Turnberry (highlight of the course by far)
6 at Ballybunion (great green!)
13 at Lahinch
15 at Old Head
14 at The Island (fairway 10 paces wide!)
13 at Royal Lytham
12 on the Old Course
18 on the Old Course (can't leave that one off!)
14 on the Kings Course at Gleneagles
1 and 3 at The Machrie
...I could go on and on!