London Hotel before Heathrow?

Haven't stayed there, but it gets very good reviews on tripadvisor: http://www.tripadvisor.com/Hotel_Review-g186338-d261739-Reviews-Caring_Hotel-London_England.html

You might want to think about staying at Jury's Inn Heathrow which is a 5 minute walk from the Hatton Cross Tube stop, and one stop from Heathrow. You can get to Hatton Cross directly from Kings Cross via the Piccadilly Underground line. There is a restaurant in the hotel, but no "neighborhood" within walking distance, so if you want to do some sightseeing or go out to eat you would need to ride the Tube again or get a bus from one of the bus stops which are at Hatton Cross Tube station. We have stayed very happily at the Jury's Inn in the past, (nice hotel, no airport noise) but due to its higher rates for the date we will be in London next, we are booked in Days Inn Hounslow, near the Hounslow Central Tube stop the night before flying from Heathrow. Hounslow Central is also on the Piccadilly Line, so no changes needed to get to Heathrow. The Days Inn looks good from the reviews, but can't speak from experience since we will be trying it for the first time.

Thanks for the feedback. Since it looks like we might be able to to get out in the afternoon, I've decided to stay in Bloomsbury, near both Kings Cross and the Piccadilly line to get to Heathrow. We can pop into the British Museum for an hour or two and have a good choice of places to eat. My choice for lodging has been The Grange Blooms but I'm also drawn to the Penn Club if I can get a discounted rate closer to the departure time.

If time is an issue, Paddington give you access to Heathrow Express. There have been delays on some of the London Tube lines due to construction. Be sure to check London Underground for the latest updates.
http://www.tfl.gov.uk/