Michael:
A trip to New York is not complete without a visit to 48th Street between 6th Avenue (aka Avenue of the Americas) and 7th Avenue. Manny's, Sam Ash, & Rudy's are still there, along with a few others IIRC. Matt Umanov's in the Village is an institution. Rivington Street guitars is a cool little shop that caters to the unusual, rare, old, and downright weird. For acoustic instruments, Mandolin Brothers on Staten Island is tops. Have fun, there is nothing like NYC.
Bill, tgo