Time/temperature for juicy roasted chicken breast?

I agree with Merrill here because of the tender, pull-apart quality you probably want. If you want to concentrate some flavor, maybe split the difference and first brown the breasts nicely on both sides, then add some stock or water to both deglaze and finish by braising gently.

I usually poach my chicken breasts, but I thought that roasting might concentrate the flavor of the meat better and make a better match against the cheese. But maybe not!

I've never roasted just the breast. I always do the whole bird.

And what, pray tell, is lowbrow about chicken quesadillas! Sounds heavenly - enjoy!

Have you thought about poaching them instead? I find that's the best way to keep chicken breast juicy. I put them in a pot of cold salted water, bring the water slowly to a simmer, cover and cook very gently for about 15 minutes (it might be more or less, depending on the size of the chicken breasts). If you want to get really fancy, you can turn off the heat when they're nearly cooked and let the chicken breasts finish cooking and then cool in the poaching liquid -- this really keeps them moist.