We went to Mount Vernon this weekend to catch the tulips in bloom. It can get awfully crowded and is very family friendly as well as tour-bus friendly. If you go early in the morning, the traffic is less but that's when the buses show up. By lunch time, the buses are leaving, but the traffic slows to a crawl as people tour the various tulip fields around the Skagit Valley.
Your other choice is to go later, which is what we did. The buses and the many people on the buses are gone, but lines are still long and the flower beds and borders are crowded with families. But it's so beautiful, you have patience with all the selfies and family shots and video recording in order to take your shot. And then you get this: