J.L.
Since you will be on a cruise you will have to bring something small. How about some lovers dice? It is 2 dice, 1 has body parts on it (arm, neck, lips...) and the other has actions (kiss, massage, lick...). This could be fun, especially combined with a cocktail or bottle of nice wine. Also, guys are VERY visual. Go to Victoria Secret for something extra special, even if it is some new cool panties. You also pack a few small tea lite candles and matches to set the mood.