Two things. First you DO want to see the pattern of the tile (why do herringbone if you're not going to see it!!) but I would go DARKER rather than lighter on the grout. Something along the lines of a charcoal, or even black.
Secondly, rather than go thru the expense (as well as the pain of getting the epoxy out of the cleft of the tile) with epoxy, try going with Laticrete's Permacolor Select. it has sealer built right into the grout, and is just about as stain resistant as epoxy, for less than half the price, and no risk of epoxy glaze, and not nearly the chance of getting grout caught up in the cleft of the tile.
Edit-- Oh, and I'm in Maine, so I feel your pain!!! LOL
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