When you go to one of the races at Francorchamps, Spa is a great place to stay!
You can enjoy the peace & quiet that you will not get at the track. Even worth your while to book a day or so extra to relax (think of the famous Baths of Spa!)
The tiny centre is full of nice little shops and some very good restaurants. Here they also cook for the inhabitants of Spa, not only "tourist grub".
Around Spa you'll find vast woodlands where hiking and MTB trails abound. The golf course is famous for its setting. And there's lots of architectural beauty to be found in the buildings dating back as far as the 17th century.