I stayed at Costello's Guest House last summer while I was in Hyde Park. I was there for a little history trip (FDR library, Vanderbilt Estate, etc).
Costello's only has two rooms. I stayed in the smaller room, the nautical room. The bed was comfortable and the room had an individual air conditioner that worked great. Please note there is no television in the room.
The two rooms have a shared bathroom, but I was the only one there for the two nights so I didn't have to share with anyone.
I chose to stay here b/c it was in my budget and b/c I thought it would be a different experience. I had never stayed at a guest house before. The owner was very nice and helpful. She let me use her microwave to heat up leftovers one night and we sat on the porch discussing Eleanor Roosevelt. She knew Eleanor Roosevelt!
Overall, it was a very pleasant experience and I would definitely stay there again. more