well, it depends what are you trying to show. if you wanna do a real close-up on a face, you'll need some 2000x2000 pixels map and a good bump map also in that size. for a body details it's the same, you must experiment to find the best solution. if you want to make close-ups i'd do it with vicky, 'cause she's less "edgy"... but then you'll need two maps for body and the face. you could do a crowd scene with far smaller map size and you can work with posette.