Odd, my gai lan in illinois summer were nothing like it was supposed to be (from childhood memory.. or commercially grown) but I think they fared the best of the several chinese choi's I tried last summer due to bolt issues. They had decent stalks (not great) for some reason, but poor leaves/greens.. odd! Those that I was slow to harvest got woody.

I think next year I'm going to try incorporating more chinese choi's during spring&fall, and not bother with them during the summer.

In short, I am also looking for advice!!

Mei Qing Choi, which I grew this summer based on recommendations on this forum, has been very successful. I direct seeded it in early summer. It had not bolted when I harvested the last of it a couple of days ago.

I'm still looking for more good chois of various types.

Jim

From my experience, the best gai lan has been the ones I grew in the early Spring. By the time it gets hotter, I would have already harvested several cuttings and am ready to pull them to make room for other vegetables. They like the lengthening days of Spring rather than the shortening days of Fall, though they will still provide a decent crop as long as it is cool.
I find that the best tasting gai lan is from the second cutting. You may get a decent third and even a sparse fourth, but that will be all.
I have some seeds of a large stalk variety that I can share. Let me know.