If your going to NY City, there is a long stretch of Park Avenue that is Pet Friendly, and cater to pets. Most stores have drinking spots and snacks for your dogs and you'll now find pet friendly hotels and restaurants. The hotels (based on what I have read), really spoil your dog when left in their care for the day.
just google Pet stores in new york and a bunch will popup! the ones in the city are much more expensive but have very cute stuff. i dont shop there though because i know i would go more broke than i already am shopping online haha~