I hold no cash for the most part. Taxable is mostly international ETFs such as VEU, VSS, SCZ, with some US small-cap value: VBR.
Tax-advantaged has all fixed income such as bonds as well as the rest of the portfolio which includes some international & US equities (including the same things held in taxable).
I use this method to get cash out of my tax-advantaged portfolio:
Placing Cash Needs in a Tax-Advantaged Account - Bogleheads
I recently had to sell some ETF that had dropped 15% from recent highs to pay for a big ticket item. You may think, "Uh-oh, he sold his stocks at a loss." That's not quite true. I sold the ETF (at a profit) in my taxable account and almost immediately bought the same ETF in my tax-advantaged account. To get the money to buy the ETF in tax-advantaged, I used money from a short-term bond fund. It turns out I bought the replacement shares of the ETF at a lower price than I sold them for and they have gone up about 5% since.
Bottom line: The method in the link really works.