I found the standard seats in the F30 to be very unsupportive and flat, and also rather uncomfortable. Upgrading to the Sport Seats was an imperative following that. My god, they're bloody excellent! I had them in my E90 too and they were brilliant in that but they're even better in the F30!
As one can imply from the word "Sport", they are supportive and hold you in place, especially if you tighten the side bolsters but they are so god damn comfy too!! Everybody who has sat in them have passed kind comment to their comfort. Like my 330d, you arrive after a long journey completely refreshed and and not stiff or experiencing aches and pains. So, just upgrade to them - they're excellent! They also look really nice, lots of detail on them and the Exclusive Luxury white/silver stitching is really nice too. The headrests are cool too and comfortable. Lots of adjustability even without having the electric seats so I'm hugely pleased once again! No regrets so far!
I didn't go for the Adaptive M Suspension because of one little letter. "M". I didn't want a hard ride, especially coming from the E90, I wanted more comfort, so I went for the standard setup. I then learnt that the "Adaptive M Suspension" is pretty much VDC as on the F10/F11 long after I placed my order, so I though "ahh shite!" VDC made such a change on the test cars I had so I was frustrated! If it was called "Variable Damper Control" and not "Adaptive M Suspension" then I would've ticked the box.
Thankfully, I really like the standard suspension and it's so much more comfortable than my 330d so I'm happy! It's also still stiff enough to feel the road and maintain composure with very little body roll.
If I knew what I know now, I would've gone for the Adaptive M Suspension because it's supposed to be even more comfortable in Comfort than the standard springs and I like how it would stiffen up in Sport mode so this is my ONLY regret on this car, but even then, I'm not that bothered by it because the standard setup is so good!
I have the 18" 398 mixed tyres on my 328i so I have 225's up front and 255's out back so traction and grip is impressive! I also got my favorite Bridgestone Potenza's back! I got these with my 330d too but then they were changed to Pirelli PZero's when the Potenza's wore out (changed by Kwik Fit because I leased through Lex, not BMW themselves) and the PZero's were louder and less aesthetically pleasing, especially on the front as the alloy was exposed more. So I'm a happy bunny, because the Potenza's are quieter and more comfortable, and also very grippy!
These are also the new generation RFT's (Run Flat Tyre's) and you'd never guess they were Run Flat's! My E90 rode heavily on the sidewalls and were rock hard and unforgiving so these new generation RFT's are most welcome! They are much more forgiving and quieter, although I can't speak for how well they wear yet for obvious reasons!
So, only 1 week and 6 days in to F30 ownership as I write this and all is going exceptionally well!
Any questions/requests on the comfort aspects, post away as I'm sure you know by now!