I have Dave Mallinson's 100 Essential Irish Session Tunes, and 100 Evergreen Irish Session Tunes. They are inexpensive, readily available, the typeface is easy to read, they include guitar chord markings, and I've found them handy for all the reasons you give.
From the lack of response to this post I feel as if I'm revealing a secret sin here! Surely other people use written music? Of course, only as a prompt for material already learned by ear...