Well, it can be a source of legitimate discussion.
Why would you marry Tashigi? I figure she'd be a strong, yet not a cruel woman. And she lacks the glaring personality faults of Nami, or the emotional baggage of Robin. Hina, well, I don't know enough about her, and it might be a bit TOO kinky.
Califa, you'd never get her to the altar. Kokoro, though, once you look past the face, might have a fun personality, as long as you can keep her lubricated with liquor.
I always thought, when it comes to potential for naughty thoughts, logia were most interesting. I only wish there were a Femme-Smoker (see PirateNeko's cosplay thread) to explore that in a socially-acceptable manner)
And killing Nami is obviously useful for the impact on the plotline. We'd probably see the East Blue ruled by a Morgan-Arlong coalition without her.