although not knowing song pretty much puts me in the dark on the sound you're going for, I would say that instead of using two mics on one source, do two takes with just one mic on the amp each time. For the second take, if you can, switch guitars, amps, mics, preamps, etc. so you get a different tone from the first. This will help your guitars sound bigger by the irony of two different sounds coming together to form one big guitar. Put a high-pass somewhere around 100 hz on both, and pan one halfway to the left and one halfway to the right.
I know this is a pretty basic default answer, but it's the best I can give for not knowing the song.