Hi Kelly, We have been at the entrance to Sunnyside a few times in recent years, and have taken photos of the gate, which says "No trespassing"...we have never been able to go onto the property, so have never seen the house, if it still remains, or the cemetery. We would love to be able to see the property, but I guess it is privately owned and apparently off limits to the public and even the descendants of the original Howe family. If I am able to find out more, I will try and post the information.
If you are able to find a copy of Listen to the Mockingbird in a library somewhere, it has a wealth of information about the family. I was able to buy a copy a few years ago online, and have enjoyed it very much. The author is Daniel Dunbar Howe, and it was published in 1961, a limited edition of 1000 copies.