I haven't set up AdvMame in a long time, it wasn't too tough when I did though. A little time consuming, but not difficult. Basically, you'll need to set up the resolutions used by each game and tweak them to display correctly on your monitor. This mainly involves resizing and centering- some resolutions won't be possible on your monitor, but there's always a similar one that can be tweaked to work just as well.
Maybe it's gotten easier since I set it up on my Nintendo/Sanyo monitor with AdvMAME .67 ?
Here's a list of most resolutions used by vertical games:
http://mame.joymonkey.com/vrez.htmlWhen setting up, you should make sure that all of these resolutions display correctly, then all your vertical cocktail games should be fine. Once they're set, you've got the most authentic looking arcade display you could ask for.
As far as front-ends go, ArcadeOS is the grand-daddy. It's still the easiest to get going on an arcade monitor too; a simple flag in the config file sets it to VGA/Arcade.