What's the best setup to transfer a digital or analog video over 100 ft?
A long VGA cable with a proper amp/spliter on the TX side, would be the simplest option. You can get good VGA cables up to 150' at modest prices from http://www.pccables.com .

Another good option is a CAT5 extender kit.
http://milestek.com/p-16209-vga-over-cat5ecat6-decora-wall-plate-set.aspx

Without a more detailed description of what you are trying to accomplish, it's hard to give a better answer than that.