When I do my sausage bake, I kind of "toss in the kitchen sink":
Garlic, mustard powder, coriander, cumin (easy on this), fennel (also easy on this), and thyme you already know about.
Also, filé powder, oregano, cilantro, marjoram, and allspice. Marjoram can overpower, though not to the extent that cumin or fennel do, so go easy there, too. Of course, I add pepper powders, but you've got that covered in your base. I like the idea of the lime leaves, too.
We really like that mix on the sausage bake, and it would probably do well in your sauce, too.