Man, I love this game.
With no harem option, I'm on my third or fourth runthrough of trying not to fuck everything up with one girl or another. I thought I was pretty settled with Vi, but then Kana played out some interesting options. Those options really made for a great scene in the end (Pun might have been intended).
Elspeth is very intriguing along with very hot. I think the only thing I would change is her eyes being green. Hey. Can't have it all, can you? Anyway, I am quite interested in seeing where things might go with her.
Amrit is also definitely worth going back to check out more in my opinion. I declined some chances with her on my current play, but having pages of save files makes it easy enough to go her route as well.
Serena is the only one from the main screen I haven't done much with outside of the early chapter opportunities. Might have to see what's there as well some time, but she hasn't really jumped out at me.
Ines... Damn. Probably one of the hottest girls in the game, but doesn't seem to have a path. Please tell me that the MC gets to bone her at some point even if it's just in a threesome with Amrit or Vi. Please.
Katie is another great character they introduced and it kind of sucks that she appears to just be a side piece at best. She is quite fun.
Now, Kana's old partner.