Both the Glimmerglass State Park and the Glimmerglass Festival Opera House list their location as Cooperstown, but in actuality the Park is 8 miles outside of Cooperstown on the northeast side of Otsego Lake, with the Opera House nearby on the northwest corner of the lake nearby. If you are going to visit one, you should also visit the other! In fact the park is an ideal spot to stay if you are wanting to take in any of the Glimmerglass music or theater productions which have quite a professional lineup in the summer season. If staying at the park you will also enjoy the amazing beach and waterfront on Otsego Lake, and great kayaking on the lake as well as the stream flowing into it. You can also hike, ot take a day trip into Cooperstown, especially for museums and all things baseball.
The camping opportunities give you three options: the main campground by the park office, which is wooded and shady and has electric hookups as needed, and is close to the beach, but you will have a lot of neighbors. If you want a quiet tenting experience, choose the Beaver Pond primitive tenting campground! This offers a small number of large, well spaced and private tent only sites set back in the woods by a beautiful pond and by the Beaver Hiking trail. Very peaceful with more solitude than the main campground, but a longer walk to the beach. The third and newest option, the Travis Field campsites, reminds me of an overflow parking area at an outdoor festival, unfortunately just a bunch of basic tent campsites plunked in an open grassy field located in between the beach and the Beaver Pond sites. I am guessing the park has greater demand for campsites than the original campground offers, so they put these spots up in an open field, and maybe folks would rather have these sites than nothing if they want a week at the lake, but they would not be a first choice unless perhaps you have a group that wants to gather together and take a block of these sites. I didnt check out the cabins, but there are some, which might be especially good if you want to come in the winter as the park is open year round