Hello Danielle,
Thanks for stopping by planDisney with your question! There are so many great reasons to stay at a Walt Disney World Resort Hotel: convenient location, incredible theming, early access to the parks, and the ability to make dining reservations and book Individual Lightning Lanes slightly in advance of guests staying outside of Walt Disney World.
Disney Genie+ Lightning Lane Entrance: Guests staying at Disney Resort Hotels don't really have an advantage over other guests when it comes to Genie+ reservations. All guests can make their first Lightning Lane selection at 7 AM, no matter where you are staying. The one benefit to staying on property is that you get to enter the parks 1/2 hour before opening, so you could ride one or two popular attractions before your first Genie+ reservation.
Individual Lightning Lanes: These are a different story, and guests staying at Walt Disney World Resort Hotels definitely have an advantage over those staying off property. They can purchase their Individual Lightning Lanes beginning at 7 AM, while guests staying off property need to wait until park opening.
Dining Reservations: Guests staying at a Walt Disney World Resort can make dining reservations for 10 days of their trip beginning 60 days prior to their check in day. This means that the reservations you make toward the end of your planned vacation could be 65 or even 70 days in advance, making it a bit easier to book those "tough to get" reservations. Guests staying outside of Walt Disney World can only book reservations 60 days ahead of time.
Hope this helps. Have a magical vacation!
Diane