is information on the Concierge Class perks on Millennium. I'd take these more as suggestions...we got most of them on our cruises. No biggie.
You've got a great cabin...the aft cabins are considered by many to be the most desirable. Your cabin may slightly larger than the one illustrated in the link, and will have a shower instead of a tub. Yet, you should find it very comfortable.
If you get a chance, dine in the Olympic Restaurant one evening. It can be pricey, but the menu is superb and the location is stunning. I usually don't do the specialty restaurant thing on ships, but I have no hesitation in recommending those on Celebrity as they are definitely worth the extra cost, IMO.