Mudder, I use 12AT7s, old NOS Mullards, Amperex and RCAs in a lot of my amps. If I have a jazz or blues gig, they work great in V1 and V2 to "gain down" the amp.
I also use them in all of my amps for reverb and effects loop circuits. The Mullards are about $30 each, last for years and sound...