You could create an arrangement for any size vase, the larger the vase, the more flowers and greens to use. For Christmas time, use red, white and maybe even green flowers (like green button mums). Also choose from a variety of greens and evergreens out there. Accent a red rose in a bud vase with some baby's breath and cedar. Deep red alstroemeria are especially beautiful. There are many other flowers that would be perfect to use for Christmas arrangements, the link below will take you to a complete list of flowers, foliage, and evergreens for Christmas floral design.
When I learned Ikebana as an adult, I was really fortunate to have had an old_fashioned sensei (instructor) who not only taught me the theory and techniques, but also immersed me in the respectable manners and ways of the good old days. It is through my sensei that I learned that Ikebana goes beyond the typical art form, and that it is more of a way of life; in fact, Ikebana is also known as kado, which literally means "the way of the flower."