Yes, definitely do it! I used to give plasma (before they stopped it) but was asked to do platelets a few times because I matched up with someone in need. Made you feel like you really had helped someone. Used to take me about an hour but I believe chaps tend to take longer, hence the hour and a half mentioned above. It takes place at special clinics as they have the centrifuge machinery necessary. And yes, you get lots more points!!
I've amassed 258 donations mostly from plasma! Latest one was this morning!