I did policy debate in 9th/10th grade, but honestly, I wasn't that interested in policy because the issues weren't exactly hot-button and the debates were more about your pre-prepared evidence than anything else. Next year I'll probably do LD or PFD debate which seem more interesting.
Politically, our debate team is a mixed bag, but it definitely leans liberal, with several conservatives, including one rock-ribbed conservative Republican atheist (quite rare) who loves to bash Al Gore.
Policy has always been... odd... I've done Congress and have experimented with PFD, both of which seem a lot more like actual debate than policy is.
Our debate team breaks down by event; LD kids are definitely more liberal, the policy kids are more Obama-backing than anything, PFD kids seem center-left overall, and Congress is the most conservative event (at least one or two conservatives and two libertarians, myself included).