Lexus = hotsauce. It's got the N/A 2JZ-GE motor in it, which is reliable to what, 700 horsepower? It's also got a TOUGH 5 speed in it, shouldn't have any reliability problems what so ever. Also has the fuel effeciency of a Camry. That's my first pick.
Second choice would be the Infinity. I'm not crazy about the styling, but it's a huge step over the 350z. Should handle well and have reasonable power, but it's not really anything special.
RX-8...not what I would consider a good daily driver.
Caddy CTS-V...heavy, depreciates quick, I'd be willing to bet gas milage is about on par with the rotary (sub-par). I would also wager that the fit and finish of the Lex or Infinity is better, even with the lower pricetag. The only Cadilacs I would ever consider would be the one based off the C6, and the Catera with a motor swap. OH SHIT, neither of those cars were actually desinged or built by Cadilac...