are they worth that much? there are probably a few key points they look for and some red flags to avoid, but other than that i dont know if eloquent prose will make the difference between harvard vs podunk med. you might be better off getting them out early instead. since they usually have length limits (even if not, the readers have attention limits), every instance of flowers is that much less substance. but hey, im an engineer, go figure. AND i screwed up mcat writing. but i did AP out of college english!
edit: in my mind there are few facets of the app process itself that can vault you to superstardom (besides credentials or numbers that you have already accumulated and that are not subject to change), but there are many parts that can damn you. maybe if you can concoct tales that will have adcoms' heads spin, but how likely is that even if you put your all into it? not to undermine your writing ability, but i mean that each reader will have his own criteria that will make his head spin. so making lots of heads spin might be tricky. ok enough