You realize the Lime Rock NASA/PDA event on the 18 is for advanced drivers only, right? If you are a novice or a beginner, you can't sign up for it. And the next PDA/NASA event at Limerock seems to be in August. The Monticello event is in May. Just point this out to make sure you haven't missed it. I think there are some BMW CCA events at Limerock before August though.
Limerock is fast and fun, but not a particularly forgiving track. I don't know anything about Monticello. I was considering it, but $350 is too steep for a day on the track IMO.