Hi there,
Planning parties are such fun! How about a Mommy & Me Tea party? Since most parents will actually stay with their child, making it a group playdate with both child and parent could be both joyous and a lot less stressful. Moms and daughters can arrive in pretty dresses and hats :o)
Other creative themes are Flower Fairies with flower halos and winga, Mickey's or Minnie's Playhouse, Tickled Pink...where everything is pink, a stuffed animal party (children can make their own stuffed animal and have a little adoption ceremony), Barynard, and there's soooo many more.
I'm a party planner, so I would also like to suggest keepig things very simple. At age two, most children have a really short attention span. Many clients have chosen to provide one game and one activity, then just allow the kids free play...maybe a little bounce house.
Best Wishes!