Annuities, high grade corporate or muni bonds, mix in some high dividend yield blue chips, etc. I'd mix with some riskier investments that were higher return on average.

Nothing is guaranteed if things go totally to hell, of course. (And I did make the qualification of not being pegged to inflation.) But unless we get to a very bad place, I think that assuming 5% on these sorts of investments is a pretty safe bet.

(ADDED: But pick your own number. 3-4% probably is closer to the really very safe modulo inflation given instruments like CDs in that range. But you're reinforcing my basic point. $2M is not really the basis for a huge annual income in perpetuity or even over a multi-decade timescale if you don't have other income streams to add to that mix.)