I have four B&W 801's, two 603's and a B&W center

The wattage you need depends on how LOUD you plan on playing them.
Normal (background) music is usually less than a watt per speaker. Loud enough to cause permanent hearing damage will need a thousand watts per speaker.
If you plan on listening at rock concert levels.. 100 watts is not enough. If you plan to listen only at moderate levels.. the 100 watts is 'adequate'... but I would go for 300 @ 8ohms per myself If I needed amps for those speakers

The N801's are very efficient. Playing very loud passages on mine I am using about 30 watts on peak passages. It is more important to have an amplifier that can handle the load they present easily.

classe and b&w are a marriage made in heaven. I'm sure there others (I have 805's and run with a pioneer elite HT receiver but can't compare to the sound I heard with the classes.

More power does not hurt. I was a B&W dealer in the days of the original 801 and found they liked to be pushed. In those days B&W demoed them at shows with an ML 3 which had several hundred watts [and sounded like c**p ] and a Crown [SL 2, I think] which had a nominal 200 watt output but which could pulse 1800 watts at 2 ohms. I had one of the Crowns myself and they worked well. My experience in recent years has been limited to a pair of older 805s which I still have; but from what I have read they still like a lot of power. I would think something like the Musical Fidelity Kw 500 integrated, which has 500 watts at 8 ohms and more at lower impedance's would be ideal. The current 550 has even more power , I think. It would drive both pairs of 801s. I have the NuVista amp of theirs and am very happy with it.