Hi Jill,
Welcome to the Moms Panel! I'm thrilled to hear that you are planning a Disney Vacation for your little one. I am a firm believer that any age is the perfect age for a a first visit. Now it is probably safe to say that she will have an awe inspiring visit with either a Disney Parks or Disney Cruise vacation - so really it depends on what you're up for.
As an avid Walt Disney World fan, It was my choice to have Walt Disney World be my childrens' first Disney Vacation, however one of the major factors in that decision was our ability to travel in the value season when the crowds were very light. At this age waiting can be extremely difficult, so we went with very low expectations and simply enjoyed the walks, playgrounds and swimming pools. When they were around two is when the attractions became an imperative part of our family vacations.
Now that being said, my youngest two have been cruising since they were infants - and I find that a cruise is all the magic of a parks vacation but more relaxed and "easier" for the parents. I shared my thoughts on why
HERE.
Good luck with your decision, and remember that even if she won't remember the vacation - YOU will, and trust me, those memories and photographs are priceless.