We always have had people with different eating habits and preferences. I started making an alternative choice in gravies a few years ago, as we had quite few vegetarians as regular guests. I am lucky to come from a family that cooks instinctively, and to have lived in Berkeley long enough to hone my vegetarian and vegan cooking skills. I never really make it the same each time, I just whip it together. The common denominator for me is to have a good vegetable stock on hand. I usually buy a packaged organic vegetable stock and go from there. My daughter Jacki is a vegetarian, so I am making some this year. BUT Jacki can not stand mushrooms, which would normally be my first choice for gravy.
So this year I am making a green onion/garlic gravy, and it goes like this:
Start with about 4 Tbl. olive oil and heat in a skillet. Chop about 5 or 6 green onions, including a good portion of the green stems, and crush or mince two cloves of garlic. (Last year I did a combination of onion, leek and green onion. You could add mushrooms and other vegetables here, just add a little more oil so you have enough to mix with the flour).