In January we found a couple of available sites at Spring Mill when trying to plan where we'd go for the eclipse, so we took them and then started looking at what the park had to offer. We started to really look forward to the park as much as the eclipse. The park lived up to expectations. We were able to do a lot of hiking. Our dog was welcome in most areas of the park (pioneer village being the only significant exception). They were planning for a ton of folks to be there for the eclipse, but the numbers were lower than expected. We had the perfect spot for viewing it right across the lane from our campsite, so it didn't really matter how many people came into the park for it. 

The only possible negative was that our site wasn't very level for our pop up. We had our leveler with us, so it didn't matter. My wife and I decided that the eclipse was simply the cherry on top of a very good sundae. We loved the park and will likely return again.