I've never been, but I've heard good things about Chocolate Works (I think that's what it's called??) in Millburn.
La Maison du Chocolat at MASH
http://www.shopshorthills.com/directory/la_maison_du_chocolat
If you don't mind ordering online an old friend of mines husband does these chocolates out of Florida but ships anywhere in the US ...
https://www.facebook.com/Howling-Moon-Chocolates-488149624570362/
I really enjoyed them and they are a bit of fun.
Not local, (you can buy over the internet), but the best chocolates I have found are from Harry and David. Their truffles are an otherworldly experience. I got some for a family friend for Christmas, and she can't stop raving about them. Warning: they *are* pricey.
Vosges chocolates! They are stupidly pricey, but such a unique, yummy experience. I think they are maybe less expensive overall than Maison du Chocolat, and more interesting. And, their packaging is beautiful: http://www.vosgeschocolate.com
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I won't be going into the City. So where are the best local chocolates? Or, where are the best chocolates to be found locally?