Oh we have a ton of songs that we use it on. Byker Hill is one of my favorites that we do, but there are plenty more than sound great with the variable tones on the Cahone (or yes Cajon as another way to spell it.)
Obligatory joke: Once I make the second large one, I’ll have quite the pair of Cahones! 
(groaaan)
I have thought about taking mine apart and lasering a really cool design on it but I am worried it might change the sound… what do you think? I mean it isn’t a perfectly smooth surface… I guess I could do the 75% that isn’t really slapped. lol
On the front playing surface? I use 1/4" plywood and so an engrave on the front should be no problem to it’s playability, and unless you are VERY precise with tones (notes) on the cahone, I REALLY doubt that any difference to the tone that might occur would be noticeable.
For the one that I’m planning on making after my GF arrives will have inlay on both the left (Band Logo) and right (Compass Rose) sides. I was thinking that the front face will have our Band Name Engraved on the front, but I was thinking of putting it lower on the face (part of that 75% that doesn’t get slapped). HOWEVER, check out the picture with the large Cahone, especially the bottom part of it. You can see the many chips and damage done to it over the past 4 years of regular abuse/use. We’ve intentionally not been “careful” with this since I can always make another one in a given weekend.