The tone settings I use are in relation to an amp modeler but some of the same principals can be used in the live micing of an amp.
For metal guitar tone, I've chosen a mesa dual rectifier style amp with a 4x12 Marshall style cab which is being miced with a ribbon 121 (which is modeled after a Royer R121 microphone). There is also an SM57 model mic but I prefer the R121 because there's a little more low end.
In front of the amp, I'm using an overdrive that is modeled after an Ibanez Tube Screamer and a noise gate. Both the amp and the overdrive pedal have very low gain settings with the amp at about 9 o’clock and the pedal at the lowest gain setting.
Besides that I also use a Para EQ at the end of the chain. The EQ is where I really dialed in my tone. I experimented until I found something I like and now use it on every single tone patch.
For leads, I simply rolled back the noise gate a little bit and added a delay.
As for bass, I've used a lot of the same things I used for guitar.
For metal I prefer a bass tone that has a little bit of bite so I've added a compressor and a tube screamer to the front of the chain. I'm using a Fender style amp with an 8x10 cab and again I'm using the R121 mic and the same exact Para EQ setting.