Caveat: I almost never buy ready-made costumes, and I use any and every excuse to wear/make costumes.
The success of both costumes depends on how you end up doing your hair and makeup. Everything else is more or less gravy. Cleopatra is probably slightly easier on the makeup front with just exaggerated khol around the eyes, and it just depends what you want to do with hair. You might be able to do something with your own hair (if it's at all close to what it was the last time I saw you), or you might want to have fun with wigs. I thought they did some fun things with Cleopatra's look in HBO's Rome. You might want to take a look at
some google images for inspiration (or watch the second season of the series. Warning: It's pretty gory, but historians generally like it.) As for clothes, something vaguely flowy and more or less solid and empire waisted will do. Carrying around a rubber snake would probably drive the point home, but I don't like costumes with props. Inevitably they either get lost or in the way.
The geisha costume will probably warrant a wig purchase, if only to get lots and lots of volume and because those knots are complicated. Makeup is also a lot more complicated, but it's probably doable with a lot of white powder and red accents and lots of pictures downloaded from the web. The kimono could be as simple or as complicated as you want to go.
ETA: I'm going as Marvin the Martian. I have the red shirt and leggings from American apparel and a green tutu on hand. And a ray gun. I just need to work on the helmet.
