I’ve found great help in reading GmatClub over the app process, so I feel like it's only right that I contribute something to the forum. I was a round 1 applicant, was waitlisted without interview in January, invited to interview in April, and then accepted in May.
While on waitlist, I showed stern that it was my #1 school. I also sent in an update on some volunteer work I did and a letter from a manager at my company who I worked on a project with describing my role. So there is hope for you waitlisters as long as you show them your genuine interest.