Wide mixes? Can't seem to get it

for me, getting a super wide mix starts with the positioning of the overhead mics. getting a realistic stereo image here will help a lot.
also, NOT hard-panning the guitars will surprisingly make the mix sound more wide when you throw an stereo imager on the master buss later on
 
dunno if this works for you but i think that two guitars panned hard left and right seem much wider when i add a third guitar in the middle.
you cold also try to add some "X" reverb on the guitars. take the left guitar track, copy it pan it hard right and add a reverb and then do
the same with the right guitar track.
 
Check the whole mix in mono. Phasing issues will pop out and make certain things disappear or thin out. Could be that the guitars are out of phase with each other slightly and are thinning each other out. If you can get it sounding wide and full in mono, then put it back to stereo, it'll sound like a whole new mix.

In general, I like to mix a whole song in mono at first, to get the balance between instruments right and then go back into stereo to do fine tuning on panning or any pan automation.
 
you cold also try to add some "X" reverb on the guitars. take the left guitar track, copy it pan it hard right and add a reverb and then do
the same with the right guitar track.

^ THIS.

I just send the left guitar to a bus (post-fader) that is panned hard right. Opposite for the right guitar. Reverb busses should be all wet, no dry. Shit can widen up your mix big time (IMO).
 
Also, experiment with NOT panning the verb bus hard. For instance, left guitar is panned hard left, maybe put its reverb at 45% right. Also, depending on the song, don't feel like the right verb has to be a mirror of the left verb (right verb could be panned at, say, 30% in the previous example).