I'm struggling with this as well, only on the other coast and with a shorter time frame (~2 years maybe). The main issues are your time horizon and risk tolerance, and I don't think there's a "correct" answer regardless. The shorter your time horizon to wanting to buy a house, the more liquid and low-risk (CDs, money market, etc.) your down payment savings should be. This gets really tricky as the time frame shrinks (18mo-3yr out maybe), as stocks could be down 40% in that kind of window, crushing your down payment, or home prices could be up another 20%+ making your cash savings less meaningful. If you're serious about waiting five+ years, I'd be almost fully invested. If you think it'll be sooner, I'd probably scale the cash % up by 15%/year closer (so 70% invested for 3 years away, 55% for 2y) or something similar to that.
I'm waiting for the SF market to cool down before doing anything, personally. As a result, I have about 40% of my brokerage/house savings account in money market and the rest in index funds/a few names I think are fairly defensive from here. This smells a lot like market timing, which I'm not a proponent of, but I haven't been able to come up with a better solution.
Note: edited my %s because I can't math.