I'm not a big believer in distance as an enhancer of love interest. I think that's a myth and typically results in one or both finding other lovers to do. Seen it way too many times up close and personal to WANT distance between one I want and myself. There is no standard distance in miles or blocks that fits the mold. "What sort of distance is better"? What does that mean? Don't really get what you're after with the question other than you sound like you want your space, and want her far enough away to not get in your way.