If you can afford it, a heated waistcoat may be the way to go - my Aerostich one going strong after ten years, one jacket does multiple bikes, and I think it's the cure for cold hands, combined with those long sports tops that go over yr wrists and have thumb loops (best one is Rab's Powerstretch half zip, amazing bit of kit, fits under other layers). Warm body means spare heat left over to go to hands.
Heated grips are nice, need hbar muffs to get the most from them IMHO.