I stayed at the Peoples Brownstone house with my son (14) and parents (both around 80). We hired a car and needed parking. The parking is free but not guaranteed to be in the same street. We had no problems though and were able to park outside in the diagonal spaces the whole time. If not it's a street up. On arrival George saved us a spot. I was not concerned about renting in Harlem after reading some reviews. However, it is real New York, not wealthy, large house New York. There are some groups of locals hanging around but they either ignore you or nod and say hi. We didn't feel at all threatened in any way.
The house is a world away from the street outside, beautifully furnished with some amazing art collected by the owners. The beds are great and the kitchen and garden an oasis of calm. The kitchen has everything you would need for cooking for a big party plus lots of things you would normally have to buy - flour,, spices, oil, butter etc. We hardly bought any food but cooked pancakes every morning.
For getting into NY (which was my main worry with my father) there are three or four Metro stations within a few blocks either side. We had no trouble getting around, especially with google maps to help. Its about 7 or 8 stops into NY - 20 minutes or so.
Carol Ann and George are great company, and one evening took us to a very local venue which you will have to visit to find out what it was. But my dad and i had a great time.