London, there are three shops you've GOT to check out.
Davidoff, Dunhill and JJ Fox (ask to see the basement)
They are all within a block or so of each other. Davidoff is a really nice shop.
Dunhill, second floor of the store, used to be a bank. See if you can check out the vault. Lots of old stuff.
JJ Fox. Down the street. Lots of old stuff. Not a lot of boxes on display, but ask to see the basement. They have so much stuff in keep for all kinds of people. American and International celebrities, as well as some of the British Royalty. They also have a chair that Churchill used to sit in and smoke...that's what they told me...it's uncomfortable as hell, but I sat it in for a picture.
I'd also try to get to Broadweighs Cigars. It's owned by a guy named Ajay who is a real gentleman. I've met him personally, and he's one of a kind.
48 Broad Street, Teddington, Middlesex
Telephone: + 44 (0)20 8977 3793
This should keep you busy...and broke. There's also a small shop in Harrod's that's run by one of the big London shops, I think Davidoff. It's expensive, but so is everything in London. Also, try to check out the Library Bar in the Lanesborough Hotel Hyde Park Corner.
Have a great trip.