For most most destinations in the world, I'd go with J flights and stay in a B&B or small inn at the destination. Personally, I find those kinds of inns have more character and intrigue anyway. And I get far more incremental enjoyment and comfort out of J vs. Y on a long-haul flight.
Of course, I'm like a lot of FT'ers in that I also love the big-chain hotel rewards. I err on the side of 4-star reliability when I'm in a large city or with family.
But when my wife and I travel alone to a destination with some interesting options, we enjoy staying at the most "non-marriott" places possible. The proprietors of those kinds of inns are always knowledgeable about their location and frequently have an interesting story to tell about their own lives.
All of that said, listen to
Jaimito: lots of good deals and promotions out there right now for properties at all levels.