I can also attest to the greatness of getting time at a racing school. I've been to a good dozen events with a couple different organizations, Trackmasters
, which is great, Performance Drivers Association (PDA)
, which is another good school. Unfortunately both of these organizations are for the north east, focussing on Watkins Glen International.
I also know that different car clubs like the Porche Owners Club and the BMW owners also rent tracks for driving schools and might let you run with them.
Just be aware, most places require an in-depth inspection of your car before you go since you are going to be on a Race Track. Some places also require you to have your own approved helmet, although loaners might be available.
And last but not least, you only get out of it what you bring to it. I've seen guys show up who think that they are the hottness and don't want to listen to the instructors tell them how to drive their car, so instead they run their brand new BMW into one of the barriers.
Cliffs notes: Driving schools are good. You should do it.