I've finally finished the redesign of the user interface for WPB. Unfortunately, I was unable to figure out how to get a multidimensional drop down menu to work so I settled for multiple drop down menus rather then waste any more time trying to figure it out. You can see the final UI design in the following screen shot...

As you can see, the UI now has a series of drop down menus, each of which will build a portion of the message to be advertised. The first drop down menu designates what roles the player needs for their group; Tank, Healer, and/or Damage. The second drop down menu will indicate what type of party the player is going to advertise for; Dungeon, Raid, Battleground, or Zone. The third and fourth drop down menus will let the player choose which instance or zone they are looking for. In order to shorten the possible lists in the second drop down menu, the player will choose which continent the instance or zone is located (ie Kalimdor, Eastern Kingdoms, Northrend, or Outland). A checkbox lets the player toggle heroic mode if they plan to do so. Finally, the player chooses which chat channel they wish to advertise their message; Yell, General, Trade, LFG, or Guild. The player can then click on the "Advertise Now" button to send the message. If the player wants the AddOn to automatically broadcast the message over a 90 second interval, they can toggle the "Auto-Advertise" feature by clicking the indicated checkbox.