Bel Aire Princess Hotel

Excellent value for money.
At the end of a busy street which has plenty of restaurant/bars to eat and drink at.
The skytrain station is just at the end of the road and this allows you to get to just about anywhere in Bangkok for between 15 and 40 Thai baht ,which is roughly 20 pence to 60pence in sterling.
Staff were very helpful and polite and there is a good massage/ spa service, which I can highly recommend, as it is very reasonable and you can have a Thai or oil massage in your room at no extra charge.
Be careful though a Thai massage is not for the faint hearted.
The massage was no more expensive than the numerous parlours along the main roads.
There is a good bar just before you get to the Bel Air (can't remember the name of it) which does very nice but inexpensive meals; service can sometimes be slow at busy periods though.

The Bel Aire Princess is described as a "boutique" hotel. Now, I don't really understand what "boutique hotel" means but my idea of a boutique is a rather self-important, consciously elite place staffed by unfeasibly trendy and finicky people who wouldn't allow the likes of me through the door. Happily, the Bel Aire is none of those things.
It is a comfortable, welcoming hotel in a great location. We arrived on an early flight and our room wasn't ready, however, the desk clerk was more than happy to take our bags and offer us complimentary coffee while we checked in. Indeed all the staff were extremely charming and helpful. The public areas are elegantly but understatedly decorated. There is a small bar (open until midnight) and a restaurant/breakfast room. We didn’t eat there but it looked very pleasant.
The rooms are large with very comfortable beds and extremely effective air-conditioning! They are perhaps a little sparsely decorated - a few more pictures on the walls may have added a bit more character. The bathroom was small but clean with a bath and shower. There is a mini-bar and tea and coffee making facilities - great for my morning cuppa!
The swimming pool is quite small - and very cold! - but a nice place to sit and relax.
The Soi (Sukumvit Soi 5) upon which the hotel is situated is very quiet and has the advantage of being near a number of bars, restaurants - Sukhumvit is a great place for nightlife - a Foodland Supermarket (with it's fantastic food bar), and the Nana Skytrain (a five minute walk).
We enjoyed our stay immensely and if you are looking for a reasonably priced hotel I would certainly recommend it.