I have different rack packages and modules that I use for my servers. I'm not brand loyal but have all IOGEAR kvms.

In one system I use two servers(4 outs), two TH2G-As (creating 8 outs), 8 4-Port VGA VDAs, and an 8-Port VGA USB kvm attached to a single monitor. This is for good old RGBHV which down 4GHz Wire is still clean and strong.

In another system I use a pair of servers. Each server has a TH2G-D (4 Outs), attached to 4 DVI VDAs, attached to 4 DVI detectives, 4 DVI over fibre boxes, and a 4-Port DVI USV kvm.

The third system config is for HD and outputs 1080p down DVI extenders.
Four servers attached to 8 Dual Link DVI VDAs attached to 8 DVI over Fibre extenders, and a 4-port Dual View Dual Link DVI USB kvm.

I have another config I use from time to time in which I use an NTI 4-port DVI multiview. This thing is a little finicky but for the price it's a great head's up on four outputs.

The kvm is nice because I can individually adjust each server. However, I also use VGA and DVI routers so I can instant failover in a problem. A simple VGA AB switch per output will usually work on VGA but DVI is a little more expensive.

Here are links to check the stuff out.

The NTI 4-port Multiview
http://www.networktechinc.com/quad-splitter.html

4-port Dual View Dual Link DVI USB
http://www.iogear.com/product/GCS1644/

4-Port DVI USB
http://www.iogear.com/product/GCS1764/

8-Port VGA USB
http://www.iogear.com/product/GCS1758KIT/