One of my favorite pastimes is exploring a gf's "nipple limits" (how hard she likes them stimulated -- some women need significant tweaking/nibbling, others the lightest of touches). Don't know about other guys, but I've found that after you get to know a woman's limits, sometimes you can surprise her by giving her a quick kiss then proceeding directly to the "limit" with your hands or mouth. For some women, they are wet and rarin' to go immediately. And as scorpio alluded to, doing it from behind can add to the effect -- "I'm horny as hell, my dear, and I want you now"...
Kev
Kev