There is more data available on cisplatin since it has been around much longer. I started out with weakly cisplatin and noticed a ringing after just one infusion (a couple of days later). This went away by the time I had the second infusion. My MO told me that this was not possible and that it was just in my head... (no kidding). After the second infusion the ringing returned and we switched to carboplatin. It is less ototoxic etc but it is myelosuppressive and thought to be less effective, hence the much higher dose.
I personally like the idea of a weekly treatment, it makes more sense to keep the drug at a more constant level than just having 2 (or 3) spikes. Also with the weekly treatment you have much more control if you do not tolerate things well.

Markus