I was thinking a good Harem idea would be a Bachelor Style Competition. Basically all the girls are competing to be your girlfriend or wife and will do anything to be with you. So basically each intro is a group of hot girls begging to be with you. You could do a general one with a variety of girls, but you could also do really specific themes as well. Some examples..
SLROriginals presents
VR Bachelor - Big Breast Edition
VR Bachelor - Big Booty Edition
VR Bachelor - Sugar Daddy Edition/Teen Wife Edition/Virgin Teen Edition
VR Bachelor - Latin Wife Edition
VR Bachelor - Asian Wife Edition
VR Bachelor - Black Wife Edition
VR Bachelor - Smart Life Partner Edition (think nerdy/intelligent/reading glasses/alpha business females)
The intro could show you sort of living in a large house with all the girls. Maybe it's your mansion and they all talk about how great your place is, and they talk about how impressed they are with how rich, successful and handsome you are, and how they want to be the one who gets to stay and live there with you. You could have small quickie type action in random parts of the house like laundry room, kitchen, couch, bedroom, etc. from girls trying to do anything to cheat to win. Later it moves towards a group gang bang contest with them all trying to outdo each other and talking dirty about how they are the best and will do anything to win.
An easier route if that is too complex an intro, would be to just have it all be a gang bang contest for the whole thing. If it's the breast edition, maybe they are all trying to titty fuck you the best. If it's the booty edition, you have girls in the background really trying to tease you with their ass to pick them.
In the end they all stand around and smile at you and ask you who you pick and it fades out with no one selected. So then you have all the comments on the video from people on who they would have picked.