three days in London with teenager, looking for area/hotel recommendations

Kesington is fine but think about Bayswater as well. A bit cheaper. Vancouver Studio Apartments are clean, safe and for London a good price.

Close enough to Paddington you can walk. 3 tube stops to use. Loads of bus lines. Vibrant neighborhood. Close to Hyde Park. Portobello market (which i think he'd enjoy seeing).

For me a perfect introduction to the city of London for the 15 year old.

Get your Oyster cards when you arrive and you'll see what a breeze it is to see the iconic sites.

Review theatre monkey before you depart to see what shows are on: http://www.theatremonkey.com
Same with what shows will have discounted same day tickets: https://officiallondontheatre.com/tkts/

For bookstores:
https://www.buzzfeed.com/danieldalton/beautiful-bookshops-london?utm_term=.fhdqqoPVVm#.qaYZZ3koox

Happy travels.

If your son loves theater and books I'd look for hotels in the Bloomsbury/Covent Garden area. I love staying in this area near the British Museum or Covent Garden and just strolling down the street to theaters, restaurants, the National Gallery, bookstores, etc. It can also be just a quick walk to a convient Tube line to Heathrow.

Paddington is boring and not particularly convenient for anywhere except the train to Heathrow.

Kensington covers a large are – South Kensington is upscale, North Kensington not so much.

County Hall and others along the South Bank are fine. Why do you think they would be difficult accessing from Heathrow? If you like the look of it and it's within budget just go for it. The South Bank is a great place to stay.

London can have too much choice.

Check proximity to tube stations (ideally, multiple stations) for places you are considering, especially on the South Bank. I don't know which areas there have hotels, but tube stations can be quite far apart, and some have only one line serving them. That means you might conceivably need to make transfers to reach a lot of destinations--a bit of a time-killer which you'd be better off avoiding on such a short trip.

Another vote for the Covent Garden/Bloomsbury/Leicester Square areas for a short stay with a teenager. Very lively, and so much is within easy walking distance. I like the South Bank, and have stayed in both a hotel and an apartment there, but it definitely adds another layer of transportation complication, something I would avoid on a short stay. I really find it worth the money to have a pre-arranged car service to get my jet-lagged self from Heathrow to my doorstep. (When you see how easy the car service is, you'll probably book them to get you back to the airport.)

I'd check Covent Garden, Piccadilly Circus, and Leicester Square areas also. You'd be in the heart of the West End Theatre district, there are plenty of restaurants, and the 'street life', such as buskers, and markets is good. All are near each other, and within easy walking distance of many major sites and very easy tube/bus rides to others.

If your son likes bookstores then I suggest the following:

Foyles--the king of London bookstores. Before modernization it was amazing. It still have everything you could want.

Waterstones Piccadilly--yes it is part of a national chain--think Barnes & Noble--but it is the largest bookstore in London.

Hatchards--a few blocks west of Waterstones. It's been there for over 200 years.

Stanfords--they specialize in travel books and maps. Amazing place.

There are also a few second hand bookstores still left on Charing Cross Road.

And, of course, the British Library.

Let me suggest the Nadler Soho hotel. While I have not stayed at this hotel--I do know the General Manager and a couple of the people that work at reception-- I have spent over 100 nights at its sister hotel in South Kensington which I would also recommend. Every room has a small kitchenette.

The County Hall area was my first choice, but it looks like it will be difficult to get to/from the airport.

It really isn't difficult to get to County Hall from airport. It just involves a transfer. Either Westminster or Waterloo stations work.

High Street Kensington is a third Underground station and the area is fairly up-market without being intimidating. It's well connected to the museum district south of the Royal Albert Hall and to the sweeping Hyde Park (where, this August, a small circus aerial school was set up to teach teens his age how to swing by their heels.) The Copthorne Tara and Holiday Inn just south of the Tube stop are both nice and mid-range price for London. Ask for the Club level at the Copthorne.
Your other resource is him. At 15 he probably knows his way around a computer and can do research for transport etc. Start him off with Google Maps and https://tfl.gov.uk/plan-a-journey/ to sort out how to get from London Heathrow to wherever your hotel is. He can also arm his cell phone to use maps from WiFi.

Pubs in this area offer Sunday feasts at the noon hour. My favorite is the Hereford Arms, two blocks south of the Gloucester Road Underground (informally part of South Kensington area). Get there before 1 p.m. as if fills up. Some customers will be speaking French in this significant "French" city. http://www.herefordarms.co.uk/

I think the area where I stayed in October would be perfect for you -- I stayed at the hub hotel at Covent Garden, which was really closer to Leicester Square. That's not the hotel you'd want as you're willing to pay more, but the neighborhood was absolutely fabulous -- as you said, interesting, lively, very walkable, right in the heart of the theater district, lots of restaurants, just blocks from Covent Garden.

I noticed a couple of hotels nearby that might be of interest for you:

-- Radisson Blu Edwardian

-- W London Leicester Square

-- Or maybe St Martin's Lane Hotel

There's also a Premier Inn Leicester Square, but I think you are looking for something nicer than that (Premier Inns are perfectly fine for me but not much charm! But no surprises either usually.)

This was a fantastic location, right in the heart of the theater district, quite near the bookstores that Frank mentions above (Waterstone's and Hatchard's, and not far from Foyle's), right by the National Gallery, a mere few blocks from Trafalgar Square.

Tube options in that area are numerous if you just walk a couple of blocks in any direction:

-- Leicester Square (Piccadilly line straight from Heathrow and Northern line)
-- Charing Cross (Bakerloo and Northern lines)
-- Piccadilly (Piccadilly line straight from Heathrow and Bakerloo line)

Leicester Square itself can be quite busy, so make sure to check out the surrounds of the hotel. The St Martin's Lane Hotel might be a bit more calm. Then again, the Radisson looked VERY nice and surely has good soundproofing.

My husband and I have stayed at the Crowne Plaza (part of the IHG Hotel Group), on Cromwell Street, South Kensington. We stayed there three different times for up to two weeks each time. It is directly across the street from the Gloucester Tube Station. It is one stop away from Knightsbridge (Harrods Dept. Store). It is a short walk to Kensington Gardens and Palace. It is a very pretty and safe area to stay in. It is also walking distance to the museum. The architecture in south Kensington is really beautiful. The hotel is part of the hotel group which includes Holiday Inn, InterContinental, Holiday Inn Express, etc. You can join the hotel program and earn points for staying at another IHG hotel in the future. I feel it is best to contact which ever hotel you are interested in - directly. I always contact their email address at the hotel itself, not just a hotel site like Travelocity.

Sorry to disappoint anyone, but Hatchards is now owned by Waterstones.

Yes, but all of Waterstones is under the capable leadership of James Daunt. I don't find it disappointing at all, it's a huge thrill for me to visit those shops when I'm in the UK!