My mom sent me some flowers for my birthday through Martha Stewart flowers and they were gorgeous. However, I had to arrange the flowers myself--the vase and the flowers are separate and the stems had to be cut. Kind of a do-it-yourself Martha-style flower kit.
Great flowers, but not the best idea for someone who is sick.
If I know there is a good florist in the area, I generally just call the florist directly. If your friend is in the hospital, call the general info line and just ask which florists send nice arrangements. They've seen thousands of flowers come through and can generally give a good recommendation.
Hope she is feeling better soon!