(This is sneaking, or avoiding detection by enemies; this is not sneak attack, the extra damage on non-aggro'd enemies)
So I am planning on making a 13 rogue 7 wizard and getting the archmage enhancements with it. Of the enhancements that allow you to cast spells for 1 SP, the invisibility option rose up as the best option to me, as the ability to keep your party invisible almost 100% of the time seemed rather cool: fights are much easier to set up, you can introduce aggro at the proper time, etc.
But I remembered reading somewhere in the starting a class guides that many higher level monsters have some form of tremorsense or other sense that allows them to always detect a sneaking character regardless of absolutely everything else in play. My specific question is should I invest in the invisibility spell for archmage or should I grab another, the broader question (which I still would like answered): is sneaking even worth it?