The question I have regarding megachurches is not how many they get for Sunday services, but how many are present on the church grounds more than twice a week. A megachurch can offer a much wider variety of ministries and spiritual opportunites than an ordinary church. Megachurches have schools (including middle and high schools), bookstores, active youth programs, young adult ministries, a wide variety of music and art opportunities, support ministries, etc. etc. It's truly amazing how these places function.
What you describe sounds like a typical large Catholic Parish. K-8 attached school, youth and adult programs, multiple daily Masses, bookstore/gift shops, etc., etc.
Many larger parishes can seat over 1000, and might have 5, 6, 7, 8+ masses per weekend.
You forgot the gym, restaurants, Starbucks, game rooms, swimming pools, athletic fields, elderly centers, theaters, etc...
It seems many mega churches have created Christian safe havens where they do not have to be either "in" nor "of" the world.