If you're going for absolute privacy and peace I'd get 100 minimum, 200 if you can. And I'd make sure there's no easements for people to drive though (like to reach another property on the other side). I got 40 thinking it was a lot, well I ended up buying the adjacent lot to keep it from being subdivided and possibly turning into a trailer park. It's really not far away at all. And now the neighbor is selling the lot on the other side but wants $2000 an acre. If he comes down I may buy it but it would have to come down in price a lot. That would put me right around 100 acres.