The soda package is well worth it if you drink lots of soda like me. The first thing I did on my Mariner cruise last year (after eating at the windjammer) was get a soda card.
They gave me a nice big coke can souvenir thing that could be used to drink soda but I never used it. Just got cokes in a glass at the bar.
Now, a tropical drink package would be nice. Too bad they don't have something like that. Or do they?
Another thing - when I got the soda package all they did was put a little round sticker on my Sea Pass card. Be sure you don't go swimming with your card or your sticker might come off. My sticker stayed on for the whole seven nights. But it was getting a little tore up after I jumped into the swimming pool a couple of times with that card in my pocket.
I think my sister had the soda package and she was getting in the hot tub with her card. Sticker started disappearing. She showed her card to some guy or gale and they put on a new sticker.