Bob, I have been to Front Sight several time. I would pay to upgrade to the four day course or look at buying a separate certificate for a 4-day course. If you can get a new cert, you might be able to use the current one you have for a skill builder class.
For first time attendees, I believe you can buy a 4-day certificate for a couple hundred bucks. As I recall, on
http://www.frontsightalumni.com one guy was selling some as low as $150.
Either the 2-day or 4-day will spend the first half day on gun safety and handling. Since the class continues to build on itself, the last 2-days of the 4-day are probably the most valuable for the experienced shooter.
If you are like most shooters, after the two days you will be wanting more. And, if you have to travel from Colorado to attend you will want to get all you can out of each trip.
Go for the 4-day class. Even as an experienced shooter, I think you will learn a great deal. Let us know how it goes. In fact, let me know when you plan to go and I might see you there.