Hi Carolina,
Thank you so much for visiting the Disney Parks Moms Panel with your question. How much fun to be taking your daughter to Walt Disney World! I am glad that you are comparing Walt Disney World resorts. Each is so unique, and where you decide to stay will ultimately depend on what you think that you and your daughter will enjoy the most.
The Royal Rooms at
Disney's Port Orleans Resort - Riverside are truly magical. It is fun to search the room for all of the clues that the princesses have been there. I also love the overall feel at atmosphere at Disney's Port Orleans Riverside. The rural Louisiana theme is so lovely and calming, especially in the evening.
Disney's Saratoga Springs Resort & Spa is also a nice resort. The theme here is of horse racing years past in New York, which may not be as meaningful to your daughter as the theme at Disney's Port Orleans Resort - Riverside, especially since you are considering a Royal Room there. The benefit of being at Disney's Saratoga Springs Resort & Spa in a deluxe studio is that it will be slightly bigger than the room you are considering at Disney's Port Orleans Resort - Riverside. If space in your resort room is important to you, Disney's Saratoga Springs Resort & Spa might be the better option. If space in the resort room is not as important to you, and if your daughter loves princesses, I would probably recommend a Royal Room at Disney's Port Orleans Resort - Riverside.
I hope that these thoughts are helpful for you, Carolina. Have a wonderful time planning your vacation, and please do let us know if you have any further questions.