About 95% of the gravy I've had at restaurants around the country has ranged from "swamp scum" to "just there".
I've always thought that gravy should not only be a compliment to a meal, it should kinda "stand on it's own". In other words, it should not only be something you want to dip your food into, it should be so tasty that you want to take a spoon and scoop up the last bits on your plate.
I have no doubt that there are many places around this country that make a good gravy. Besides my house, I know you can get good gravy at Massey's in Fort Worth (thanks Matchstick Man), and at Hill's Cafe in Austin, TX.
I'd love to hear of other awesome gravys, white or brown, around this great country of ours.