I was just thinking about this today! My boyfriend and I have been living together for a few months, but these past few days we've been moving into a new apartment, plus different work schedules, my belly dancing class, etc. So last night was the first night in probably a week or more that we had sex and I noticed it was a LOT better than usual! It probably helped that I kind of teased him a little bit (when I got home from work and changed into my belly dancing outfit, he had been taking a nap and I hopped on top of him and started kissing his neck; probably the fastest he's ever gotten an erection hehe) but then I had to go to class and when I got home, it was ON! He was a lot more passionate too, grabbing me and holding me as though to say, "I missed you so much". So yes, I think the waiting really adds to it, on a physical AND a mental level.