When have I reasonably earned a state sticker?

It's your map so it's your rules. That said, you asked what our criteria was for marking our maps. Ours is an overnight stay at minimum. Others say they mark it if they've spent money in that state. Whatever you decide, it's up to you. There's tons of stuff to see and do in every state. We like to visit State Capitol buildings. So, you could use that as your criteria. The world's door is open for you. Enjoy what we do....Dennis