Honestly, the best crowd calendar you have is an actual regular old calendar. Is it a major holiday? It's going to be busy. Is it Spring Break? It's going to be busy. Other than that, for the rest of the days, the "crowd calendars" are just educated guesses and I've found them 50/50 at best, so I just use my own eyes in the park. You can tell pretty early in the morning how crowded the park is going to be.