I've been jotting down all of my house rules lately, and in general trying to tweak the game for the needs of my group with giving the system a complete overhaul. I don't want to gut any classes, nor am I driven to hit upon the perfect solution for caster/martial disparity (which I don't think is as bad as many believe), but I do feel it could be improved upon a little. Had an idea that, hopefully, will take a little bit of wind out of the higher levels spells without gimping casters early on, and was wondering what the community thought about it.
It's pretty simple - just altering casting time of RAW based on spell level. 1st-3rd level spells are unchanged. 4th-6th level spells have their casting times increased to a full-round action, if they aren't higher already (a special exception to the usual rules, Quicken Spell still makes these a free action). 7th-9th level spells have their casting times increased to 1 round, and can never be quickened.
Thoughts?
I actually like this approach. It gives high level spells a bit of powerful magic flavor that you know from movies and stories. Where one would usually have to do some sort of complex ritual or something to pull off such stunts.