For me the CP is a must, but I love back roads and cornering. The regular M5 handles this well, but the CP gives you a bit more feel and a lot more confidence.
Also multifunction seats as mentioned. Soft close doors and comfort access are pretty cool. 360 cam is good for parking in awkward places. I'd say the only upgrade would be sticky tyres so you can get the power down in 2nd and maybe 3/4 of it in 1st. I wish mine had land keep assist and radar cruise. Mine hasn't got split fold rear seats, but that's not an issues for me.
Really tho it all pales into insignificance once the engine is warm, you hit a nice stretch of open road and let it rip... Big speeds are very easily achievable and the acceleration is pretty intense in every gear! The smile on your face will be priceless
