1 Spyglass... As far as pure golf it is simply an awesome test and you get both holes along the open dunes and wonderful tree lined holes. A true monster, much tougher than Pebble IMO. The coastline holes at Pebble are unmatched IMHO, but the overall course is not as good as Spyglass.
2. Royal Melborne... Years ago I was lucky enough to get to play there. I hadn';t played much golf yet back then but took it all in and realized just how awesome the course was. The bunkering was devastatingly tough for a player without too much experience.
3. Pebble Beach... The coastline holes....beautiful and challenging
4. Merion... Short and brilliant... Fast greens (lightening). And of course the wicker baskets!
5. Saticoy Country Club (Private course in Camarillo Ca.) A hidden gem. Not a drop of water and none needed. Canyon style golf, very tough and don't get above the hole, three or four putts might be in the cards.
Two more California courses I've played worth a mention are
Sandpiper (Santa Barbara)... It is called the "poor mans Pebble Beach", and lives up to the name.
La Purisima (Lompoc)...Other than Spyglass this is the toughest course I have played. Played through rolling hills terrain, when the wind is up and your off the back tees it is game on.