The Key is located just off Sukhumvit...
The Key is located just off Sukhumvit soi 19. The entrance is actually off of soi 19, so it's a little hard to find at first. The taxi drivers don't know a lot about the place, but there is a large sign hanging from the building.
The area caters to a lot of Japanese, so the hotel is decorated in a very Japanese style. It is quite small, and has no pool or restaurant. But it is very clean, very well maintained and the staff very friendly and helpful. I booked a double room, and guests are not a problem.
They provide a breakfast, which you must choose from a list the night before and it will be delivered to your room at a time you specify. It is very basic, but everything was very tasty. You could choose either a continental breakfast (croissants and juice) or a Thai (joke/congee with shrimp, chicken or pork and juice). My only complaint is that they completely forgot to bring the breakfast on the first day.
The bathroom is large enough, and had a nice shower. The only complaint was that the towels were very cheap and thin.
The mini bar is well stocked and reasonably priced.
It is well located, very near the Asoke skytrain station, so it's very easy to get to just about anywhere you want to go.
After checking out, I went to Hua Hin for Songkran. Upon returning to Bangkok I regretted not staying at The Key again. I can attest that there are much worse places in Bangkok, at much higher prices. I would stay here again.