When I need to utilize bell service on arrival, I typically bring something hanging inside a garment bag. Even without a large suitcase/multiple pieces of luggage, the awkwardness of holding a garment bag while checking in makes asking for assistance seem very natural. Sometimes I'll have an overcoat on arm, too. If I'm not required to use bell service on the way out, I can just fold the clothes and the garment bag place them inside a small rolling suitcase (and wear the overcoat instead of carry it). I've not done any assignments that require a discreet departure, but it seems my strategy would do the trick.