We are doing both.
just recently bought Ambassador and the pack came in a few weeks. Using the BOGOF at IC Sydney for club room. Been upgraded to a eastern harbour room from a city room. Saved about $650 on the cost of the Saturday night on the club room. Not bad for US200 spend.
then on Jan 1 will be buying dining rewards program. Ups me to Platinum which will be valid until Dec 2017. Not sure what happens if I don't renew my ambassador in September 2016 though !
Ive vey also heard mixed stories that if you get "promoted from gold to platinum" intercontinental send out a new ambassador package to reflect your new status. Some people have said that includes another BOGOF voucher others have said it doesn't and others said they didn't get a new ambassador pack at all so it seems to be pot luck on that front.