I think we should do it like this, as there any many people with many different and personal perferences, we should create a couple of basic styles. What I mean is something like one fixed (800px), one fluid, one for vbadvanced. These are the typical and most obvious first things i see that vbulletin boards differ from each other.
How about just customize a theme which looks pretty cool at a simple look but when mods are added they look like they blend in with the theme? remove annoying things perhaps like gradients, fonts borders and just replace them or customize them?