I stayed 5 nights at the Casa 400, which is a few steps from Amstel Station and very close to my office. It's a decent, clean, business hotel, with very little amenities and delicious all-you-can-eat breakfast. Internet wi-fi is free and works flawlessly, the bar Upstairs is an ok place to have a drink after work. It does the job for a reasonable price. I wouldn't stay there longer than a week, though.