Nigel,
Here is the location of the RoadRacing worlds Race school/track day listings.
http://www.roadracingworld.com/guide/detail/?guide=2&guidecode=schools
The only two schools that I know of that "include" a motorcycle are Freddie Spencers School (not on the RRW list for some reason), and California Superbike School (Keith Code). Freddie uses Honda 600RR's and Code uses Kawasaki's (think 636 or 600's).
if your coming in the summer time, then Freddie Spencers school is out of the picture. He is located out of Las Vegas, and due to 110+ temps there in July, they don't run in the summer.
Keith Code runs at different locations around the country all year round. In the past he has always tried to get a Laguna Seca date VERY close to the races there (normally just after the event).
In Northern California you have Laguna Seca (Monterey), Infineon Raceway (used to be called Sears Point, Sonoma) Buttonwillow Raceway (Bakersfield), and Thunderhill (Willows, north of Sacramento).
For the summer time, I would recommend either Laguna or Infineon. You won't enjoy yourself at the other tracks in 100+ temps. Laguna and Infineon are close to the ocean, so they tend to be a little cooler, and that makes for a fun day at the track.
If I think of anything else, I will add it here.
Thanks,
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Charles Gallant