After 30+ years on bike, I finally did a track day a couple of years ago on my GS1150 at Cadwell with Hopp Rider Training and it was absolutely fantastic. No cars pulling out to worry about, a great tarmac surface and the chance to hoon along with fair abandon. I had no idea my bike would lean quite that far over (chamfered the centre stand a bit) nor go round corners that fast. For a big fat bike it embarrassed quite a few race replicas round the circuit.
The down side is that it's a day's ride either way to get there but a huge amount of fun. Hoping to do another next summer all being well.
Look in for Track days + events