bezels arer not really of a importance for any system after the 32bit generation psx, saturn etc,
i do not use bezels at all i prefer a) native widescreen or b) a stretched image to cover the entire screen.
start up sreens to mainly transition between launchbox/bigbox and actual start of game with possible info displayed while you wait for that to happen.
a custom timer to allow users to fine tune for each system/emulator ... as everyones setup differs ssd/harddrive/network drive that timer will vary so a easy way to set it.
pause screen - most consoles have a pause already builtin so i assume this is handy for arcade titles? not sure what to think of it.
loading screen between transition of selecting game then waiting for emulator to load, load up say cache etc (ps3, wii u ) etc is more important to me and how i use launchbox