For you hoarders of miles:
I had two elderly people in my life that died a few years ago. My grandmother and my great aunt.
When my grandmother passed, my mom cleaned out her residence and found all the gifts she had given her over the years, in the cupboards, unused. She was saving them for a special occasion. She never had another special occasion and died at the age of 89. She was saving all those things/experiences for a future that she never took an opportunity to have.
My great aunt, on the other hand, died at 87, and before she died she told me she had regretted plenty of things she had bought, but had never regretted spending her money on one thing: Experiences
She said every penny she'd ever spent on concerts, plays, and lots of travel had enriched her life in many ways and she could treasure those memories always. She never had any regrets from serving in WW2 in the Red Cross in Australia, living in Paris for a year, travelling to the East Coast, South America, etc.
So...what are you waiting for??? Life will always get in the way...unexpected illnesses, job changes, 3 friends who recently found themselves unexpectedly pregnant (but that was a blessing), etc etc. If you don't use the miles today, you might not have time tomorrow.

Just a thought, and a lesson from a wise old lady, my late great Aunt Edy.