While the idea of "Wish: what is it good for" is a worth idea, attempting a RAW optimization of that last clause
You may try to use a wish to produce greater effects than these, but doing so is dangerous. (The wish may pervert your intent into a literal but undesirable fulfillment or only a partial fulfillment.)
seems... well, problematic. That "try" and "may" in there give a DM plenty of latitude to read it as "what happens is up to the DM" -- and the only way you can optimize your DM's response is to actually work with him, not against him. (Regardless of how much latitude your DM reads into that last clause, few DMs will react well to you actually pulling out a densely legalistic wish-wording that all but double-dog-dares the DM to find a remaining loophole.)
It seems to me if you're really going to try to optimize the "greater effects" clause you've got to try and optimize your DM *wanting* to give you more than the standard clauses -- either by talking to him about it in advance, by using your
wish to undo the effects of some spectacular run of bad luck or the effects of the DM screwing up (i.e. casting "fix blown-up plot"), or simply appealing to your own DM's sense of the cinematic.
