acoustic guitar plus keyboard friendly songs

First, welcome to Chordie.  I look forward to your input. 

As far as songs for keyboard and guitar go, pretty much every folk, country, alternate country, rock and alternate rock song ever written, plus nearly all jazz songs. 

That said, Crosby, Stills, Nash & Young songs feature both guitar and keyboard and may be a good place to start.  Also Willie Nelson is a genius with country soloing and regularly features his sister playing a honky-tonk style piano, so you may want to spend some time in Youtube looking those up. 

- Zurf

Welcome to Chordie! I would suggest that you have a look at each other's music collection, or just discuss your favourite artists and find the common ground. I'm sure you will soon come up with some music that you both really like and can work on with enthusiasm. If a song is not really working for you, put it aside for later and try something else. I'm assuming that you are playing for yourselves, rather than with a view to gigging. But there are very few songs you can't do with guitar & keyboard! And as joeyx3 says, they don't have to be carbon copies...
Cheers!

I've spent a large portion of my existence strumming along behind my papa's piano... As long as its in the same key you can play anythig together. Check the music store for books that have sheet music with guitar chords above it. Piano and guitar work well together, and it'll be even better if you put a personal spin on your favorites. Music is universal, even the artist originally used an electric guitar and a bass or whatever doesnt mean you cant play the same notes with a keyboard and piano (and your uniqueness will make it awesome).

All You Need is Love

Welcome to Chordie Chicov22!  I don't think I can add anything here that hasn't already been said.  Let us know what you come up with though, I'm curious to know what you figure out as I'm often finding "piano" songs that I adapt to guitar!