The big penis. If you had $100 million, you could have sex with a new girl every day for the rest of your life, but that\'s meaningless if you can tell they\'re all faking it.
If you\'re that rich, they may not even be faking it. Women perceive resourcefulness as sexy. This is why intelligence is sexy, why an abundance of wealth is sexy. It\'s built into them evolutionarily-speaking. Big muscular arms imply not only the ability to protect, but to acquire \"resources.\" On the flip side, men perceive fertility & shape as sexy. A vessel to carry his offspring. That\'s why we\'re far more visual creatures when it comes to the physical aesthetics of the opposite sex. THAT SAID, we\'ve also evolved to acquire an attraction to other characteristics like humor, personality, character, etc, but I don\'t think that removes us from our innate criteria for mates.
Also, I know a few guys with \"big\" even \"huge\" penises that don\'t necessarily get laid frequently (or much at all). Also, most normal women aren\'t readily taking an 8 x 6.5 and I\'d venture to say most (normal & average women) would prefer it a tad smaller. At least with a bank roll like $100mill, you\'d have some sort of sex-life guaranteed lol.
That said, had I been where I was pre-PMMMA, this would have been a more challenging question. But given my current state, the $100mill EASY.