I have a 100 watt amp what kind of a attenuator should I get? 100 watts or 150 or 200.
Depends on how much you're cranking it. If you only want a little bit of powertube break up, then the 150 should suffice, if you want to dime that mother, then definitely go for a 200. 100 is definitely not enough.

I know you didn't ask, but definitely look at ted weber's stuff. His MASS line with a speaker motor does a great job of not sucking tone.
I don't give a shit if you listen to me or not
ya im going to have that baby on 11 like nigel. Thanks for the help man.