Dajax my band is basically a three piece with a singer who also plays some harp.
When I approach songs on guitar I try to fill in all the key things that stick out. Whether it be a horn line, or guitar. Makes it fun for me, also being a three piece you dont have to worry about getting alittle out of key with the other guitar player. I invert chords, switch from minor to majors in the middle of songs just to keep myself amused, plus the bassist in our group and I just play off each other at times and take songs in whole other directions. Doing these things creates a musical tension in familiar songs that people who listen cant put thier finger on but makes all of our performances special in some way, cause we dont just paly songs by the book. I may learn a song note for note but over time it becomes our own song, played our way. The essence of the song is still there for the casual listener but the musicians really seem to dig the way we turn them inside and out.
Take a song like Roadhouse Blues, weve played it a million times,but in the middle the bassist and I will do these wired harmony lines together and when the harp comes in, the singer and i do a trade out, he plays a line then I mock it, then back and forth. Being a 3 piece allows for this freedom that Ive never found playing with another guitar or keys for that matter.
Just take whatever song you are playing and put your stamp on it and make it your own.
Good Luck and Keep On Rockin!
"A winks as good as nod to a blind man"