If you notice these things aren't computer monitors anymore they are really HD TVs. I heard that computers were going to do away with the analog VGA video outputs and go to the same digital connection (DVI and HDMI)used by TVs. So here you have it.
As for the cable length I see no problem. If you check they are made in much longer lengths- 60+ feet. I know just because they have cables that long doesn't mean that they are good to use but again I don't think there will be a problem since this is digital not analog.
If you do have an instance where you have to go longer (usually when HD TV's are used for advertising or signage) there are converters for each end that will put the DVI or HDMI onto a couple of CAT5 cables.
-Hal
