My idea of a better UI is to NOT have to type in the slash command, instead, have the people that are on my guild, or my friends, on the side of the interface. If you need an example, I can post a picture of what "I have in mind".
AuldLangSyne? See.... We're not quite sure on what you want to do...
__________________
"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff, The Tao of Pooh
I use MiniFriends for this and it's the only one I've found that does it this way (assuming I'm correctly guessing what you have in mind)... I hope this mod never breaks because I'm not sure it's being developed any more.