The rose-garden at Longwood is not that big as that in NY Botanical Garden. It has only couple of rose species compared to more than 650 species and more than 6000 rose plants in NYBG. Also the rose-garden is separated from a big central court-yard type area where the whole area is surrounded by rose arbors and arrangement of plants in pots.
Orchids: Longwood has a huge collection of orchids. They can be found at various locations in the conservatory and in open-ground. However, a whole large section of the conservatory is especially designated for orchids. Here are the pictures of the orchids from that section.
It has a huge collection of palm, cycad, ferns and other exquisite plants. According to its website, Exquisite flowers, majestic trees, dazzling fountains, extravagant conservatory, starlit theatre, thunderous organ—all describe the magic of Longwood Gardens, a horticultural showstopper where the gardening arts are encased in classic forms and enhanced by modern technology. More information and pictures would come in later posts. It also has a huge store and sells really nice perennials, among other things, which I do not find in any garden-centers in NJ. They are also cheap :-). So, I ended up buying Sneezeweed, NY-Aster, Windflower, Rose Mallow and Bluebeard.