*Looks at Dating sim convo.*
*Decides to add my 2 cent in the form of a single penny to the mix*

Luna would be a tough one too, assuming you could date both genders, since by the time she's no longer underage she's going to be seriously committed to doing what she thinks is right (so much so she becomes famous, but more on that later).

Mayt would be a roller-coaster, what with memories of people that aren't him and all.

Mithera, however, would definitely be one of the easier characters to [s]get in bed with[/s] date, since she's so... Playful and carefree. 

Melina would be a bad idea. That's all I have to say on [i]that[/i] subject.