I like to use poultry seasoning because its combination of herbs tastes like Thanksgiving to me. But feel free to use whatever seasonings you like. Thyme, sage, rosemary, onion powder, and garlic powder in various combinations will give you a similar flavor, and you can increase the flavor by adding any of them along with the poultry seasoning.
Add nutritional yeast. I often add a tablespoon or two to increase the richness and the flavor of the gravy.
Make this fancy by sautéing onions, mushrooms, and garlic (or any combination of the three) before adding the other ingredients.
Add smoked salt for a "bacon gravy" flavor.
Use more non-dairy milk for a creamier gravy. (In these photos I used 2 cups broth to 1/4 cup cashew milk. You can use up to half non-dairy milk.)
For extra flavor, add a little vegetable bouillon in addition to the broth.