Float has no say on the matter with regards to width. I use an extremely simple 14 line grid system that uses % widths, is nestable, and works in every browser I test it against.
While simple, it's definitely way more elegant than some of the grid systems I've seen built, such as the popular 960 fluid grid layout that ultimately generated nearly 800 lines of CSS for 5 columns.
It also goes hand in hand with the core principles of OOCSS, which essentially states to extend classes and use multiple classes per element.
Sorry, I should have clarified in stating fluid width layouts. I'm a much bigger fan of pages that specify the width as a percentage. Or that at least use max-width/min-width so I can expand the pages as needed. Every grid system I've encountered fixes the width at 960px or 980px. I've found floats are the best, but by no means, only way to achieve a fluid layout with a variable width.
