Glossy coating can make a dull screen look somewhat better. It definitely makes colors look more vibrant and improves perceived contrast. Some say it even makes the viewing angles a bit wider, although I haven't verified that. Under it I am pretty sure that, on average, it's the same crappy TN panels.
I believe you are correct about this. For instance, my Samsung 2343BWX and Dell sp2309w monitors probably use the same 23" 2048x1152 panel, but because the Samsung is matte while the Dell is glossy, images on the Dell look somewhat more pleasing.
I for one view everything in full screen mode. I hate horizontal scrolling, and unfortunately, to have no horizontal scrolling and still enough usable horizontal space for two windows side-by-side you need at least 2048 (twice XGA).
For screens narrower than 2048, I partially overlap the two windows.
it's been my experience for most users, vertical resolution is more important.
To me, vertical and horizontal are more or less equally important and that's why 1920x1200 is my favorite laptop resolution: it's as tall as 1600x1200 and as wide as 1920x1080. For a long time I tried to like 2048x1536 but eventually gave up because its pixel density on a 15.0" screen was just too high.
Quite a few of my colleagues have resorted to turn their external widescreen monitors by 90 degrees in order to have a better vertical view for their work tasks. While this may sound silly, it actually makes a lot of sense for some work contexts.
I don't find this silly at all because I have been doing it for over 3 years. Have you seen the photo of my computer/monitor setup in my office: http://forum.thinkpads.com/viewtopic.php?t=52525