Rides being down during your return window are honestly the best thing that can happen to you. Disney will issue you a Multiple Experiences Pass
- It has no return time
- It can be used on the ride that was down or similar tier rides
- It does not count as your current LL (so you can book another one
One of my favorite "hacks" is to book a ride that is currently close if it has a near return time. One morning I had a Splash mountain booked for ~15mins after park open. About 30 minutes before park open I got an alert that it had switched to an MDE. I was able to book Space mountain for ~1hour after park open. I started the day with 2 LLs in my pocket (for 2 mountains) and adjusted my rope drop strategy to avoid big thunder (since all the splash rope droppers would end up there).