I'm not applying to PhD programs this year, but I thought I might reply anyway. I took the GRE with about a week's preparation and got 710v, 800q, 6.0aw. Was disappointed with the verbal score because I'd been scoring 790s on ETS's free test prep software, but the percentile was high enough, I suppose. I'd been majoring in the physical sciences before I switched, hence the quantitative score. For the aw section, I had the feeling that there were certain things the readers were going to be looking out for, and tried to provide it. Similar to what the above posters said: clear writing, etc. I might just have been lucky though.
At my undergrad institution -- which isn't in the Leiter top 20 but highly regarded in general, I think -- the sentiment toward GRE scores is that it won't help you if you do well, but it is likely to hurt your chances if you don't.