I would disagree on the coriander bringing in the citrus... SWMBO's wit (Wife's Wit) started out with 1/4tsp coriander. I have slowly increased this and now I add .75oz (5.5G batch). The increase's have been slow and steady, and I'm about where I want it to be. The citrus flavors come from types of citrus used. IMO, fresh zest in the last 15 min of the boil is the way to go. I have tried the dried bitter orange peel in my first attempt at a wit, and the fresh is so much better. I use the zest of: 1 Grapefruit, 3 oranges, and 2 lemons, per the recommendations of a book I read on the subject. If you want the book name I will need to dig it up. I don't remember which one right now.
Cheers
Preston