Clydenora,
There are some similarities between Boma and Restaurant Marrakesh - both feature grilled meats. Marrakesh has several couscous dishes, and Boma sometimes has couscous on the menu. However, they're different enough, and are very different experiences -- Marrakesh is table service with entertainment (belly dancers), while Boma is a busy buffett. The chefs at Boma work right behind the buffett in an open kitchen, and are available to answer questions and make suggestions. The desserts are very different, and Boma has a big variety of soups, too.
There's such a variety there that you should be able to enjoy both restaurants on succesive days.