From a quality perspective, the inputs are in this order:
composite (the A/V plugs) < s-video <<< VGA < DVI or HDMI
i.e. s-video is better than composite; VGA is much better than s-video; DVI and HDMI are identical and are slightly better than VGA
Realistically, VGA is plenty good enough. You're not likely to notice the difference between VGA and DVI/HDMI on any monitor of 24" or smaller ... and an LCD TV, no matter what the size, will have at best HDTV resolution of 1920 x 1080 ==> the SAME pixel density as a 24" monitor.
The cost of running the cabling -- assuming the distances are all short enough that you don't need signal amplification (which can add a good bit to the overall cost) -- will be lowest with s-video (but I don't recommend using that); then VGA (as I noted, this is probably the best connection to use); and then the most expensive with HDMI and DVI cables. I would suggest you determine where the displays will be placed, and determine the number and length of cable runs that you need -- and then simply price out the different cables [Monoprice -- noted above -- is indeed a good source for cables].
As for distance -- you can reasonably run s-video, VGA, or HDMI up to 100 feet, as long as you use good quality cables. DVI should not be run more than 50 feet. All of these can be extended further with the use of repeaters.
