As you say, keep your head on and don't get so excited that you don't check things properly. There are a lot of threads on this board with quite detailed checklists, but most look too detailed to be practical to me.
What you really need to check are things that there will be no comeback with once you've left the forecourt - so check the paintwork, wheels, interior for marks and scratches. Also check you have all the unattached bits - 2 keys, logbook, iphone cables etc. Also check that all options ordered are present and correct. Apart from that it's up to you, if there are mechanical / electrical issues, etc it will generally be covered under warranty..
I'm supposed to be picking my BW7 GTD up next week so I'll be using this advice myself (if I don't get too excited!)