Food: Grab some Omakase at Miyake, located at 468 Fore St.
Head over to the kitchen-ware store up the block (on Fore St), same side of the street as Miyake, and right around the junction with Exchange St.
Go up Exchange St. to take a look at abacus gallery for some really creative pieces (they'll give you some great inspiration, especially for interesting gift ideas)
Nearby, be sure to grab some lobster-- the prices are usually good and fresh lobster tastes really sweet and tender. If you go to a lobster pound, keep in mind that those specimens are not necessarily caught right there in the river.