Once it is set up, MAMEWAH is about as simple as it gets, I think.
When it's launched, you get a scrolling gamelist, and hit 1-P Start when you find a game you like.
It takes a little work to get it set up the way you want it, but it is very configurable.
Using the layout editor, you can display just about any information you want about the games, and can change the pictures to show what you want them to.
Once you get it the way you want it, it's pretty much dummy-proof.