I've done 54 holes while playing different courses a few times. Here is what I've done in no particular order:
1. A Jim Engh day that included Fossil Trace, Red Hawk Ridge, and Pradera.
2. Ironbridge, Sonnenalp, and Country Club of the Rockies in the Veil, CO area.
3. Spyglass Hill, Poppy Hills, and Spanish Bay
4. A 63 hole day that included Buffalo Hill, Big Mountain, and all 27 holes at Eagle Bend (Montana).
5. Both Whitefish courses and Meadow Lake in Northern Montana.
There are probably others but those are the ones that come to mind.