I like the quality of the Claroatats, and you never
have to clean them.

I use Allen Bradley or Clarostat sealed 2 watt plastic conductive
types with the slotted shaft and lock nut. These are fairly
cheap(compared to a ten or 25 turn pot) and well made.

PS 
    If your amp doesn't use pcb's and there is plenty of room I'd go
with the chassis-mounted pots because they seem to be much more
durable. Unless it is a vintage and you'd rather not drill another hole
in the chassis. (BTW regular trim pots are easier to mount on an
eyelet board; the leads on the cheaper cermet trimmers can be
broken very easily...)

. One advantage with the multi-turn pots is that you can usually
dial in the desired bias voltage without having to replace all of the
bias resistors a few times until the voltage is in the proper range. (I
usually end up replacing the resistor to ground just once to get it
right.     ) So if you don't mind experimenting with the bias
resistors you could try using just a regular 10k trimmer. That of
course depends on the amp... on a Peavey Classic 30 I really
wouldn't want to take that mofo apart several times just to fine-tune
the bias circuit! 
Steve Ahola 

 Thanks for the info Steve, just don't trust those lil legs in the bias!I
guess I'll get out the drill and put in another manly 2watter, hell it's
just a fugly homebrew!