While attending a conference in De Westergasfabriek I stayed in Holiday Inn Express for one night. The rooms are comfortable and spacious enough. The airconditioning is great, it works like a charm while you don't hear a thing! I had a room on the station-side, which can be noisy due to the trains or intercom. I could not sleep without closing my window, that's the only downside.
The hotel is located near station Amsterdam-Sloterdijk from which you can take a train to Centraal Station (central station) and start your visit to the center of Amsterdam.
Parking is available for about €20,- a day, which is kinda expensive.
The breakfast was just ok. If you, like me, want an English breakfast you'll be disappointed. They "only" have fresh bread, yoghurt, fruit, etc. No scrambled eggs, sausages, beans or whatsoever.
All in all, good hotel for 1 or 2 nights.