As for me:
Sort out careful yet effective investment strategy, emphasis on cautious capital growth. Steer clear of stupid spending and you don't need that much to live on. Perhaps property- no buy-to-let-pricing-others-out-of-housing-bs, but genuine, large-scale, social housing. Charging enough to get an above-inflation return on the initial investment, and not much more. Would be quite fun to ask a managing agent for his rent valuation and then tell him, no, half that.....Look after the dearest (none of them near, really), buy an suitable plot of land somewhere and build a modest passivhaus on it (as much for tightwaddery as ecofriendliness). Would need a very large garage/bike shed though. Might actually learn to drive, get a car or three. But mostly bikes. Some high end carbon, maybe a Ti, definitely a couple of Moultons. And a velomobile or two. And perhaps a bike factory. Viner apparently in deep financial trouble, would ensure any problems with mine get sorted

As for what I'd do: Whatever it was, lots of time cycling. Touring, long audaxes, whatever... Probably keeping LBSs very happy indeed. Not interested in 99.99% of 'normal' holidays, might do the following-bands-on-tour-thing sometime.