Guiness or porters, TO ME, are great paired with a chocolate e-juice, the one I employ being ECX's chocolate liqueur.
Not an IPA fan so much, but I would think it could go one of two ways, either a BOLD or spicey flavor or a very MILD flavor, that would suit your palate. IPA has so much body and spice, to me, anyway that I would guess the more mild flavor would suit me personally. For you, who knows, try anything and everything until you hit upon the right one(s)!
Good luck to you in your quest!
Carbon