if you need the extra seating space then get the third row option.. bear in mind you will lose the spare tire "feature" since the third row folds into that space...
the second row w/o third row seats do not adjust.
as for the sound system... i ordered my 08 w/the standard sound (12 speakers, and 205 watt amp)
it sounds very nice and can be raised to a nice and pretty loud volume without problem... (i believe this system to be enough for most...) but..
i still like my music just a little more louder and with more bass so the premium sound would have been a better option for me...(16 speakers and 600 watt amp)
i am now upgrading the speakers to aftermarket ones to do the trick!
no matter what you decide you'll enjoy your new ride!!! it's pretty awesome!!
welcom to the board!!