There are a few places that come to mind....and I've run races...or at least RUN....in all of them.
Avenue of the Giants Marathon, about 40 miles south of Eureka CA.
26.2 miles run about 85% under the shade of huge beautiful redwoods.
Joe Henderson once said it was the most beautiful course he'd ever run on!
The 17 Mile Drive around Monterey/Carmel CA.
I ran a 14.3 mile race one time there, striding past the mesmerizing ocean and perfectly manicured golf courses and magnificent gnarly trees.
College Cove, a nude beach about 1 mile north of "downtown" Trinidad CA, which is about 25 miles north of Eureka.
Never ran a race there, but there was a stretch of beach which, at low tide, you could run without having to swim, and it measured approximately 660 yards each way, thus making it a 1320 for one round trip.
I would generally do 6 round trips, for a distance of about 4.5 miles!!
Can't recall the exact location, but I ran a 14 mile race on mostly trails near Victoria B.C. one time.
I arrived late (Had to hitchhike there!!), so they allowed me to start with a time-adjustment.
Trinidad-Clam Beach Race--Dubbed the Humboldt County Olympics, it's an 8.5 mile race run 6 miles on hilly gorgeous scenic one-lane road for 6 miles, then the final 2.5 miles on hard sand.
It's optional to remove your shoes as you cross the Little River soon after hitting the beach.
All of the big names from Humboldt County and Humboldt State University have run the race.
Chuck Smead, Gary Tuttle, Danny Grimes, Mark Conover, Marilyn Taylor Allen, and too many others to list.
A place I'd LOVE to run/race, but never have, is in or near Jasper, Alberta, in the Canadian Rockies.
However, I HAVE hiked its trails.
There are NO words to describe its beauty!
As for the perfect track race....I've already run that....many many times!!
I've had the privilege of running MANY times on Hayward Field's track!!