Long post ahead everyone...
Thanks to everyone who helped out with my questions today! Now that I have everything booked I want to share about my most exciting redemption yet!
Back story: Two years ago, my father-in-law had a massive heart attack. He was home alone doing yard work when a neighbor found him in cardiac arrest and started performing CPR. He was shocked three times before they brought him back and spent the next two weeks in a coma. We're not sure how long he was actually "dead," but it affected his brain and he had to learn how to walk and talk again. He spent 8 weeks in the hospital and rehab before he got to come home, but, incredibly, he walked out of the hospital on his own. He was self-employed and the breadwinner, and has been unable to work since then as he no longer has the aptitude and focus, nor the fine motor skills, to do the type of work he was before. If you talked to him today, you would think he'd had a stroke because he has poor balance and slurred speech. All of this has been tough not only emotionally, of course, but financially as well as my mother-in-law attempts to make ends meet as my FIL continues with a variety of different therapies to try to regain some semblance of who he was.
Fast forward to present day, and a good friend of ours sent us a link to a neuro institute in Florida that has been doing spinal injections on stroke and TBI patients, among others, and is seeing truly miraculous recoveries in terms of speech and mobility. I mean, I almost didn't believe it until I watched videos of several different patients' before and afters. My MIL called and did a phone consult and the institute said my FIL sounds like a great candidate to receive the treatment and has an appointment in December!! We are all thrilled and are hoping that we will see some good results for him, as he is now to the point that he's so self-conscious about his voice that he will hardly speak. While the procedure is not prohibitively expensive ($6,000), it is an unexpected expense for my MIL. Then there's getting to FL... (now you see where churning comes in).
As soon as we got the news that he had an appointment, I told DH that I wanted to cover the expenses for their trip. My MIL is very resistant to us helping with anything (I have to track down the waiter in restaurants to pick up the bill), so I knew I had to be sneaky. I've been keeping an eye on Jetblue and Spirit flights to FLL, and saw a great UR redemption on return Spirit flights for their trip at 3,600 URs each. I texted her this morning and asked her what day they were planning to come back from Florida after the treatment and once she let me know, I booked their return flights and sent her the email confirmation! I know it's not the fanciest of redemptions, but it's a direct flight at a decent hour and they won't need anything more than backpacks for a two day trip down there, so no baggage fees. Before she could argue with me about it, I booked them two nights a Doubletree two miles from the doctor's office on Hilton points and forwarded her the confirmation for that too. She told me she didn't want me to use my points when I could use them for something else for me and DH

I told her I was saving the URs for the Disney trip we're planning to take them on next year, so she could buy me a snack when we get there to pay me back
I still need to do flights down there, but I don't like how late the Spirit flight puts them in, so I'm going to wait and see if Jetblue has a sale and probably book that.
I'm so excited for this trip that I'm not even going on, and really hoping my FIL can get some much needed help!