Fluid layout isn't a problem -- line-length is. Anything beyond about 50 ems is too long for most people to read comfortably, and multicolumn layout will only work effectively if a spread of content can be restricted to a single screen before scrolling becomes necessary (ever read a multicolumn PDF with a minuscule typeface?). One can easily float the major elements around so that screen size can be accommodated, but allowing the text in any one container to expand beyond a usable width is poor design by any standard.
Believe it or not, horizontal scrolling is not obvious to users -- many (and by many, I mean a number verging on fifty percent) ordinary end users simply cannot see horizontal scroll bars -- and is therefore not a solution to anything, but a problem a designer should avoid creating in the first place.
Horizontal scrolling is a significant enough problem that Jakob Neilsen has seen fit to name it one of the top ten web design mistakes and include a prohibition in his home page usability guidelines. I can tell you from experience supporting corporate apps that the best way to hide something from users is to make it big, red and flashing, but make them scroll right to see it. Circles and arrows and a paragraph explaining that they have to scroll right to see the Egress are of no help at all; they have been conditioned to vertical scrolling only.
And that is besides the fact that mice only have vertical scroll wheels. (Unless, of course, you have the new Apple mouse that supports two fingered horizontal scrolling.) So horizontal scrolling is difficult people because they have to actually mouse over the scroll bar, click and drag. Once again the exception is the MacBook in which a two fingered scroll on the touchpad can horizontally scroll.
I think that is the real reason why people hate horizontal scrolling.
I get the distinct impression you haven't done a whole lot of usability testing, and I get that because you're offering a lot of advice that I would have given before I started paying attention to real-world usability and accessibility issues. Being disabled gives one a slightly different perspective. Trust me, horizontal scrolling is a problem for most users, even if it's obvious to you, and having a footer in place to say "this is where the vertical page ends" just exacerbates the situation -- they see the page as unfinished and will hit the refresh button more often than they'll attempt to scroll.
