No matter if the two guitars play on top of each other rhythmically or not, what helps is to use different pre-delay settings on the verbs on their respective opposite side to add contrast between the two guitars on each speaker. What is important is that the dual mono panner that is towards the center side is creating the divider/separation line within the stereo field, that divider line is then offset by the pre-delayed reverb. So when you have one of the guitars panned 100%L on the left panner and C on the right panner, then the divider line is at the center and the guitar is occupying the whole left part of the stereo field with the divider line in between your eyes and the guitar is now also active in the SIDE component. That particular separation is fairly unpleasant for the listener, therefore it also helps to offset that line using the pre-delayed reverb. Keep in mind though that when you have two guitars to fill the stereo field, you don't need to pan each guitar as widely, you can for instance pan the first guitar 100%L 50%L with pre-delayed reverb 25%R and the second guitar 100%R 50%R with pre-delayed reverb 25%L. When you need more air in the center you can then lower the pre-delayed reverb, so that the guitars shift towards their sides and become more separated as unique on each speaker. Therefore the pre-delayed reverb volume faders become fairly powerful during the balancing process.
When you add the pre-delayed reverbs on the guitars, find room for when they ping back in the arrangement and in the stereo image so that you can hear them more easily and hence don't need to add so much gain. This means you have most signal left and lots of air. So when you mix, think of the air factor a lot. The air is incredibly important to create a lush sounding mix that does not exhaust the listener. Analyze the arrangement to discover how various sound sources eat up the air inside of the mix. The air is lost both by fighting rms levels and fighting peaks, both peaks and rms need to be handled for air. As a mixing engineer, learn to perceive the mix also from a rhythm perspective, this is especially important when working with guitars that are often strumming and playing rhythmically and important for succeeding with delay and reverb. To succeed with this you can use your ears, but it really also helps to add dedicated focus on how the sound sources fit rhythmically within the mix. You can for instance solo each sound source and contrast it against the drums, then as each sound source contrasts with the drums in a nice way, you can add two sound sources in solo against the drums and contrast those and so on. You can do the same when you work with the warmth of the mix, now the vocals are the sound sources you contrast against. This will really improve your mix, it will sound like the drums become much more alive, although it is really the surrounding sound sources that make the drums vital by creating space for the drums and interesting rhythm interactions. Similarly, the vocals will sound warm, although it is the surrounding sound sources that make them sound warm.
When you work with air, keep in mind that some of that air should not only be used to utilize the stereo field more effectively, but also for adding warmth to the mix. That's why you need so much air, because else you have no room for adding warmth and rhythm, and no air left after it for allowing the mix to breath. (= emotion)
So it's not only about maintaining a clean airy mix, paradoxically you also need to "add" rhythm to the mix to make it as exciting as possible, which you do in many ways, e.g., with delays and pre-delayed reverbs. So do not think of these moves from a tool perspective, think of them more from the perspective of why you use them to create what type of mix qualities, focus on the mix qualities. A mix that does not utilize the stereo field effectively can be improved.
When you pan the sound sources that go towards the sides, monitor also the SIDE component so that you maintain a good balance on each side, this will help you pan more effectively. Also be aware that if you have one side that has its fundamental frequency at say 1 kHz and the other that has its fundamental frequency at say 1.5 kHz, then the mix will sit a bit off. So try to balance the fundamental frequency between each speaker, you can for instance put two spectrum analyzers on top of each other and compare the frequencies visually on each side.
It can sound nice to have the drums sitting above the guitars in the mix, but that's also a matter of taste.
