Layout: I have all of my game clients stacked on the lower left of my screen at 1680x1050. This leaves an area 110 pixels high at the top and and another area 240 pixels wide on the right. I have these two areas being filled with DxNothing windows.
The top area on the left shows the attunement of any RK's I have in my current group. Underneath that, I show the XP bar for all toons which are not 65 yet. To the right of that area, I stack the targets of all clients in a 2x3 area so that I can monitor everyone and make sure they have the correct object targeted.
The area to the right of the targets has the ability to rotate feeds. The one pictured is a look at the quest logs for all the toons. This helps me verify that everyone has completed a quest (killed enough mobs, picked up enough random objects). With a press of a button, those feeds are replaced by a view of all of their maps. This helps me view which direction quests are in case I'm leading with a 65 who doesn't have the same quest. Another press of the button, changes the maps into inventories for everyone. You'll see the inventory open on the screenshot above. I'm using a plugin called "Hugebag" which allows me to make a square inventory window with scrollbars. The feeds are all interactive so I can scroll everyone's inventory from the feeds at the top as well as use items if needed. This is useful for quests when you have a flask and have to fill it with water or something like that. Just walk into the water. And click the flask in each inventory across the top there.
The window on the right is just used to display their chat windows. This helps me monitor IMs, XP gains etc. These feeds are also interactive.
On the left side of the screen in the center, you'll see a stack of click buttons. I use these to monitor the current state of my IS script and as well as make changes in how my group works. I can turn combat mode on/off, following on/off, targeting from forwarding through my main to always trying to select the nearest mob before executing their next skill, controlling rotation type for Captains (Healing or DPS), Minstrels (Healing, DPS Melee or DPS Range), number of RK's which are healing and DPSing, damage type of RK's (lighting, frost or fire) as well as whether healers are healing or not (to control agro, I turn them off if I don't need the heals but still want the rest of the toons to dps).