First off I recommend staying near Hyde Park, close proximity (within walking distance) to great food, shopping districts and the Underground. I'll recommend the London Elizabeth Hotel.
Parkwood Hotel
http://www.parkwoodhotel.com/prices.htm
Served by Underground station "Marble Arch".
1 minute walk to Hyde Park, 100m to Oxford Street, main shopping district of London.
GBP 99 per Family (double bedroom and twin bedroom, i.e. 2 room suite) room, includes tax, service and free breakfast.
GBP 79 per Double-bed bedroom (single room) discounted if staying 4-6 nights.
London Elizabeth Hotel
http://www.londonelizabethhotel.co.uk/bedrooms.htm
Lancaster Terrace · Hyde Park · London · W2 3PF
Walking distance to station "Lancaster Gate"
Next to Hyde Park
GBP 125 per family bedroom per night sleeps 4 people, some Family rooms have 1 room, some 2 rooms, check availability when booking. No 7th night special offer
GBP 125 per Classic Twin room per night (7th night is free)
GBP 145 per Deluxe Double or Deluxe Twin room per night (7th night is free)
Prices include VAT and full breakfast
Best Western MORNINGTON Hotel
http://www.bestwestern.co.uk
Close to London Elizabeth Hotel above, same walking distance to station
GBP 119 per room (max rate). Min rate (requiring pre-payment non-cancellation, GBP 92 per night)
Only Standard Rooms available. Either 1 Queen bed or 2 Single beds per room.
Includes buffet breakfast, didn't say if VAT included, take for granted not.
Best Western Shaftesbury PADDINGTON Court London
27 Devonshire Terrace, Paddington GB London, England, W2 3DP, Great Britain
http://www.bestwestern.co.uk
5 min walk to Hyde Park
5 min walk other direction to Paddington Station
Free internet access
Different sized rooms, all have either 1 Double bed each or 2 Single beds each.
GBP 149 (weekday rate) GBP 189 (Fri-Sat-Sun rate) per night. Lower rates available subject to non-cancellable advance payment.
No mention of breakfast but I think it is free.
Temporary Stay Suites and Apartments
Normandie Suites
165 Knightsbridge
London, SW7 1DW, UK
+44 20 72253632
No website can't check rates
Close walking distance to Knightsbridge Station
Hyde Park Suites
http://www.london-house.com/
11-13 Inverness Terrace, London, W2 3JL, UK
+44 20 7727 1711
2 mins walk to Queensway and Bayswater stations
Also closeby Paddington and Lancaster Gate stations
Points of interest within walking distance - Oxford St, Portobello Market, Baker Street, Nottinghill.
FROM GBP 670 per week Family Studio
FROM GBP 740 per week 2-Bedroom flat
FROM GBP 1420 per week Duplex flat
Internet service payable, self-catering