It's not all that configurable; most of it is frippery - colours, recalc, circular things, do your dates start from 1900 or 1904 (no, seriously, you can choose that) and because of MS's insistence on being backward compatible with both Excel and 1-2-3, there's a number of options to do with that. None of which are of much substance, taken in isolation.
Excel is inherently flexible.
Out of the box, and with no configuration whatsoever, it can be used for complex financial analysis, arbitrary data-shuffling, or balancing your chequebook.
ObExcelRant: Why bother configuring how the fuck many files are on the MRU? Why can I only have a maximum of 9? Why can't I have that list go as far down the screen as the menu will reach? What if I'm using more than 9 files and want to keep track of them? Cheers, Microsoft. I now get to use the utterly fucked up "history" option (in Windows) or the "fuck you, it doesn't exist" option (in OS X).
I had high hopes of this being fixed in the generally superior Mac version, but it's not.
And another thing, while I'm ranting about Office. Word's crap, right? Graphics handling, numbering, fields, all utter shite. However. Instead of fixing that, Microsoft decided that what we need is Sparkle Text. What the FUCK is that about?
And don't even get me started about Access.