Neither my husband or I, or my parents (in their 70s, with some limited mobility) had ever cruised before. It was a wonderful trip! We sailed out of Miami (my parents stayed at the Embassy Suites near the airport prior to sailing, and got the "cruise package" with transfers to the port). We flew in the same day and got an easy cab ($24 from the airport to the port).
We spent the extra money for the concierge level and would do it again. For the extra $150 per cabin, the complementary champagne (and maybe other extras, I don't know if everyone got fruits and snacks and their water pitcher refilled during the day, turn-down service with chocolates, etc) and the balcony view was well worth it. Treat yourself if you can! Literally, my favorite part of the trip was our cabin stewards asking "Did you have a nice day, Madam?" It made me feel like royalty!
I didn't take advantage of any of the spa services, but for no charge, I loved the fitness facility (Take a set of headphones with you to use on the cardio machines) and the AquaSpa cafeteria (open for breakfast and lunch with almost no waiting and wonderful health choices!).
Cabin 1015, Celebrity Century: Perfect location, super quiet, loved the view (Even did yoga on our balcony one morning...how perfect is that?)