*G should allow you to reserve a seat in the front of the plane ("premier" section), but you still need to call close to the flight (I always give 'em a call about 24 hours in advance).

Also, you do get priority on the upgrade list - I'm not sure how exactly they sort it, but my experience is that the UG list takes into account your status.

Not sure if they have changed this, but *G used to be able to use the first class check-in counter (not the FCL or FCT). At outstations, this is the Business counter.