Been playing GT5P way too much lately
Private rooms are the one thing I really want! So many rammers and crap racers online. I pretty much race only 750pp Suzuka, and due to all the sand traps, one bump and it takes ages to get back on track.
Otherwise, online is heaps fun (and can earn LOTS of money, quickly!).
For all thing GT related (specifically GT5P):
http://www.gtplanet.net/forum/forumdisplay.php?f=189