Hey Scott...choosing your ski for the majority of what and where you ski is key. Also, being honest as you are by truly understanding your current capability as a skier and where you expect to be. I also started skiing in my late 30's and understand what you're are experiencing.
Having said this, you'll want a ski that's easy to initiate turns with, I think one that has an adjustable binding. This feature allows the skier to find the sweet spot on the ski around the fore/aft balance and center of mass.
Keep in mind skis with turning radius of 14-16 meters are ideal for eastern skiing AND certainly capable of skiing powder boot high with good technique. You'll want a ski that emboldens confidence while you're improving. I THINK THIS IS CRITICAL!
Personally, I would highly reccomend the Fischer RX6 for you. That ski has plenty of forgiveness, and with your current skills, easy to initiate turns and versatile. Given your desire to improve, this ski would probably be a 2 season ski and very enjoyable to ski NOW. The RX 8 would be a 3 year ski but would require certainly more attention and stronger skill sets to enjoy.
I would hope that you would have a chance to demo both.
Expanding your search,? demo when you can but, look for a ski that you can feel arc beneath your feet, one that helps take you into the turn, one the allows you to finish the turn when YOU"RE ready and one that matches your favorite ski outfit..

Keep us informed on how things go,
Best,
Gary