I run games with a large but definite amount of options turned on, but the default for other options is off. I will allow extra stuff if it seems reasonable and it fits the campaign, but that leaves out quite a lot. Besides the unbalancing stuff, there are lots of options that disallow just because I don't feel like using them myself, but would be virtually obligated to for some bad guys if the choice existed. Also, there are many prestige classes that aren't unbalanced, but have powers that seem silly or too superhero-y for the campaign I am running.