Slopes are not at all crowded
There isn't more terrain
A-Basin is a sweet mountain. With that said, it is not at all a beginner mountain. Beginners stay away!! Intermediates, you will love it, thrill seekers should hit up the west wall. What I love about the mountain is it has a local vibe, challenging terrain, quality snow, and the best part is how open the terrain is. I have been there dozens of times and each time it is more enjoyable.
This is paradise for anybody who wants space to carve some turns. The lifts are slow, but this is an advantage. Slower lifts = less people per run. High speed quads dump hundreds of people onto the runs. The slower lifts slow down the flow of people onto the runs. You might miss out on some run time, but you gain a higher quality experience for each run. Additionally, even though the runs are a little shorter, the plus side is you can cruise the run without burning out your legs. With everything combined, any decent skier/rider can find a great time here. The more you explore, the more fun you will have and grow in your abilities.