yeah, you're pretty much way off.
Buttermilk is definitely the most beginner friendly, but outside of the park runs, it's anything but crowded. Start there for sure. Rarely ever a lift line wait.
Aspen Highlands is NOT a beginner friendly mountain. It has its easy trails but most are Intermediate and higher. It can feel more crowded than it is because the mountain is basically one big cornice to which most all of the slopes fall off of. Locals favorite.
Snowmass would be the second best option for you. Huge area to ski with a fantastic amount of easy wide open blues and greens. Definitely a mountain that has something for everyone. This is my fourth winter here and i find new stashes all the time. Some of the best beginner trails are right off of the main 6pack lift at the mid station.
Aspen Mountain, if not a powder day, is a snowboarder's nightmare. Most everything on the upper mountain funnels into one area that gets very crowded and very bumpy. It definitely has some classic, unforgettable runs, but most people know those spots too and bump them out pretty quick. if aspen mountain is a must for you, be off of that mountain by 10am when all hell breaks loose.
None of the mountains have much, if any, of a lift wait.
hope this helps. enjoy, i sure do