Spire (or Platinum) normally does not get you anything at ICs. And Spire in my experience is not worth much. Somewhat better rooms and occasionally club in a CP.

Ambassador usually does not get you anything in the other IHG brands.

Two completely different animals.

You need to calculate if the cost per night is worth the 200 $ for Ambassador, especially staying with points where he major benefit room upgrade does not apply.

You always can get lucky and get more, but don't count on it.