This isn't my sort of game, but I really like the models, so...
Some comments:
The first girl is all anal. The second girl is none. I'm thinking a bit of balance would be in order. ;-) The first girl's pussy must be aching for the PC after however many months the games takes place over, and the second would be so cute staring into your eyes as you enter her backdoor.
Also, as the early game has little really to do as you develop your relationships (as in, it's bleedin' forever before you actually have sex with the first girl), I think I'd expand the photography bits. One, the models are cute and you only get to see them for like 2 seconds at a time. Two, it would be an avenue to fill out your slave roster. Three, it's pretty traditional for photographers to sleep with their models. ;-)
I think I'd have a model who wanted more work approach you before a shoot (e.g. the redhead), and offer some extra-curricular activities if you'll feature her in your photos. Keep the random aspect, so if the client wants the redhead then you get playtime and money, but if the client wants the blonde, then you forfeit the money for playtime.
You could even make it strategic -- if you want to sleep with the blonde, then never photograph her, even if the client wants it. She'll get more desperate for work, and then offer herself up to you.
Have the sex ratchet up in the usual manner, maybe lewd pics for your personal use, then a blowjob, then a titjob, then vag, then anal, then group play.
If you wanted to actually get them in the harem, add in behavioural training -- okay, but you have to wear this outfit; okay, but you have to put on this collar; okay, but you have to use this toy; okay, but you have to call me master -- until she realizes that she likes her situation and is no longer just roleplaying, and moves in with you.
Anyways, that's my 2¢ on how to better integrate the photography bits into the game.
Cheers.