The Nurburgring is a bit more than a few hours from Zurich (nearly 5 hours from Basel, and its quite frankly in the middle of nowhere). However, they have recently opened a massive new village with new hotels, and those hotels may include a spa or spa services.
The ring is an easy place to have a day at the track, because it is a public road. So he does not need to tag on with a specific group to get some track time. You can pay per lap or pay for a bunch of laps. But I would check their website to make sure it is open to the public on a weekend that you want to go.
On the downside, it is a public toll road. So anyone and anything can go on the track. I mean, you can even see buses. There are no corner workers for safety, and the track is narrow so there is not a lot of margin for error.
You can find info on the Nordschleife here:
http://www.nuerburgring.de/en/feel/g...dschleife.html
There are lots of tracks in France that may be closer than the ring. But you would have to check calenders and see what groups are attending, then try and sign up with those groups (for example, there is a track at Dijon that gets rented out all the time by Suisse car clubs). But unfortunately, most tracks are conventiently located in the countryside, so finding a spa facility nearby could proove difficult.
I'm just getting to know some of the European tracks myself, so unfortunately I can't offer you much more info than that.