Personally, I like silver on most of my horses. I reserve gold for sorrels, palominos, and buckskins. As far as brightening and whitening color, I like the Quic brand of shampoos. On a silver bay, I would use Quic Color (they also have Silver for greys/palominos/whites and Black).
I prefer gold rings / turns (and burgundy nosebands look great). I think even though they have flaxen manes and tails, most silver bays seem to be warm toned tint to the m/t and body to my eyes, where silver blacks are cool toned (so I prefer silver on them).
Thanks everybody! Here is a picture of the horse in question last year:
I plan to clip him today, and expect he'll get his color back darker than last year. As you can see, his mane especially looks dusky as he gets more silver in it, and my main (or mane I guess har har) concern is that it will look dirty in the ring--not sure if I should try to brighten it as much as possible or use a shampoo that darkens the silver. I appreciate everyone's advice--I do think a burgundy noseband would look good, and silver/gold sounds like a good compromise.