Our experience with morning glories has been positive. I don't know that they do quite as well here as they might in a slightly cooler zone, but overall we enjoy them while they last.
A couple of things we've noticed over the years:
We've had success with planting varieties in succession. Some seem to mature at different times and begin blooming.
Ours seem to prefer a little tough love--not too much fertilizer or it grows more and blooms less.
Some years we have loads of blooms on everything and other years it's a little less profuse. Since we harvest our own seed or replant volunteers, we figure that may be a cause.
The variety we've had the most blooms and hardiest plant in general has been Grandpa Ott. It's a deep purple.
This year we had trouble getting our blue ones to grow and bloom. Maybe because we used old seed.
We have our vines in full sun, morning sun only, and dappled light. Several are in pots with a trellis and good potting soil, a few are in amended garden dirt growing along a fence, and two sprouted in the ditch in the backyard and grew up the fence even though the light and soil are dim and clay, respectively. Those two are faring the poorest in terms of nice green leaves, but they have quite a few blooms.
We don't use any pest control on them. If something wants to chew on them, another vine will eventually replace it. They seem to multiply over night. We enjoy the bees that are drawn to them, and while the bees are around, they usually pollinate our vegetable plants so it's a win win.