Hi Holly,
Unfortunately, it's not a simple answer. It will depend on when you are visiting Walt Disney World, if any package deals are available, where you are staying, how long you are touring the parks, etc.
The only way to know for sure is to price out both options.
I would suggest looking at one of the value resorts (All-Star Movies, All-Star Sports, All-Star Music or Pop Century). Explore ways to save by visiting www.mousesavers.com. A good place that I've used personally for discounted tickets is Undercover Tourist.
Look for
Special Offers! Very often, I find purchasing room only using a discount offer, discounted tickets and paying out of pocket for meals saves our family money. However, in the last couple of years, I've priced out packages that were much better deals too.
An Authorized Disney Vacation Planner can help unravel the myriad choices that you have when visiting WDW. I recommend Dreams Unlimited, Enchanted Destinations and Mouse Fan Travel.
If you need further help, let me know your specific dates and I may be able to pinpoint the best option for you.
Happy birthday wishes to your daughter!