I was a member of the Arlington-Fairfax chapter (in Centreville) back in the 90s. To get in back then, you had to get on a waiting list and when your name came up, do 6 hours of volunteer work on the property. And you had to keep your membership current or you were back in line again.
They have/had a decent property, with shotgun, rifle/pistol, archery, and air rifle ranges...but the suburbs were encroaching and the Karens were complaining about the noise, resulting in more restrictive rules. Of course.
I hung out almost exclusively on the shotgun ranges, which is why my buddy and I joined. Bull Run is fine, but at IWLA, you and a friend could get a range to yourself if it wasn't crowded and pull targets for each other, focusing on where you had issues, and then pay for what you used. That part was great. 100%.
The issue we had back then is that we would often show up on the weekend, after driving 30+ minutes to get there, only to see that the guy who ran that part of the club would have it partially or fully shutdown to members so he could hold a competition, open to folks from outside...and then we ended up going to Bull Run anyway. Perhaps our timing just sucked, but it really started to bug us. Of course, in the internet age, it would probably be much easier to check out the schedule before you make the drive. And the guy who ran that range put in a ton of time to make it decent, so I don't want to slam him.
I can't comment on the pistol/rifle range because I didn't use it much. It was 100 yards and only open for a brief period on Sunday, which made Saturday more crowded. Probably worked better for people who didn't have traditional M-F day jobs.
ETA: I see you are looking at Loudoun instead. I took a tour of it once and my general impression was that it was not nearly as nice as the Arlington-Fairfax chapter, but that was 20+ years ago.