I agree with all of the above recommendations above about DEMOs! You absolutely will not be prepared for the radical difference that shaped skis will make and the only way to really find out is go out and demo as many different skis as you can. All of the classifications are completely different that what you're used to; now there are race, all-mountain, free ride, freestyle, high performance, all-round, etc.
I'll be 59 before this season starts and have been skiing for 30+ years. I stopped for about 5 years from 1993 to 1998 and shaped skis happened while I was away. What a huge difference! Even after being off for 5 years I was able to ski all day, every day on our 8-9 day ski trips. My wife and I rented demos for years at every resort that we went to so they were always the latest models.
You don't mention your height which is pretty critical for length suggestions. I'm 5' 9" 160-170 lbs and I used to ski 198 skinny skis. On shaped skis I ski 170cmcm. Unless you just want to do high speed cruising on blue runs (unlikely given your background) go shorter rather than longer, especially since you're getting closer to 50.
Don't buy skis just for your Killington trip. Every resort I've been to has several slopeside ski rental shops that rent high performance demo skis. You can rent them for a week and try out a different pair every day if you want. You won't be sorry!