British Airways has introduced one of its fairly typical winter sales for travel to London, with reasonably generous airfares combined with one free night of hotel (for one person traveling alone) or two free nights of hotel (for two people traveling together) at a small selection of three and four star hotels in London.
Prices start at $412 roundtrip from New York, including the hotel stay, but not including about $190 in government taxes and fees. The fares are only on sale through 26 October, and are good for travel any time from 21 October through 3 April. The usual sort of restrictions and rules and weekend surcharges and so on apply, and full details can be found on BA's website.
The value of the free hotel room equates to about a $150 saving, depending on which of the hotels you choose, so take $150 off the airfare/hotel bundled price to get a feeling for what the underlying airfare is. I've stayed at several of the hotels featured, with my favorite probably being the Lancaster Gate Hotel and my least favorite being the Royal National Hotel.