The Gantry system is very impressive but are we stuck with a template width of 960 pixels for every site.
The ability to select both a pixel width (any pixel width) and a percentage width would be very helpful. This very option is available in the T3 Framework by Joomlart.
It is possible to have custom width but in order to do this you need to modify the whole grid setup. I build my own grid builder that allows you to set the nr of columns width and margin and it auto calculates and generates the complete css for you. But not all designs scale well, Juxta was fixed width background etc so that looks weird .