Save Local has a deal on today which gets you and a friend/partner one admission to the Russian and Turkish Baths in the East Village for only $35US. That's 50% off! The Baths have been around since 1892, and have served NYC as the place to experience an unexpected paradise. Their facilities include five saunas and steam rooms, a cold plunge pool, roof deck and a restaurant.
I have visited the baths many times myself and really enjoy detoxing and relaxing after a crazy week of sightseeing and indulging.
To find more about the Russian and Turkish Baths please visit their website.