The core question is about the roommate situation. And in this case, WHY is more important than WHAT.
In the greater LA area, $150k is moderately good money. Unless she is servicing a mountain of debt, she is far above a subsistence level life. So why the roommates and why "no men" allowed? Are these roommates actually GF's, co-workers, renters, or some combination? Why does she need (or want) to do this?
An avid traveler has figured out how to travel often and maintain a home base without needing live-in friends.
I typically drive this kind of discussion by asking her to tell me how she manages her funds, what are her biggest expenses, and how well is she funded for emergencies. This info can give me a pretty good idea of her income, expenses, and free cash flow. From there I can talk about how I am most interested in helping her. I often talk about the difference between "needs" and "wants." She may want a new BMW, but she probably only needs a Kia to get around town. She may need a new Gucci handbag. But she may only need a durable, functional purse (which can be found at Target or perhaps Macys).
I explain to my POT's that I am all about helping her get what she needs. But I am not interested in covering all her wants, though Daddy (and only Daddy) may decide to splurge on her from time to time.
If she is still onboard after that, I'm usually ready to make an allowance offer. The range of the offer might be based on some recurring monthly expense, like car payments, insurance or even rent. I will structure it like this:
"Ok, you need to cover $700 a month in car payment and insurance. If we meet twice a month and I help you with $350 each meet, you will cover your auto bills (except gas and maintenance)." This sets out a structured baseline for negotiating. She can reject, counter or accept, but now she's thinking in terms of covering recurring expenses for her needs, rather than her aspiration for stupidly expensive crap that she doesn't need.
We look forward to your M&G debrief if you decide to go that way.
Life is good
The Cat