For taxable accounts: just VTI
For retirement accounts: VTI and BND in the asset allocation that you’ve decided you’re comfortable with. For me, my total asset allocation is 90% stock and 10% bond, but for tax optimization I don’t hold my bonds in taxable accounts, so taxable is all VTI and retirement accounts have more than 10% BND to even it out.
I don’t invest in the VXUS or BNDX. For stocks, I feel like I get plenty of international exposure with just buying the US market since companies do business globally. And by not explicitly purchasing on international markets, I feel better protected since the US markets have more regulation in place to protect against companies cooking the books and other things that can cause massive price crashes. As for bonds, I’m buying bonds to reduce my total portfolio’s exposure to risk, so I don’t buy international bonds because I don’t feel that they’re less risky than US bonds.