Best post race food, for me, is The Longest Day race out at UBC. Held in the summer on a Friday night, it's always perfect weather for a run. Food includes bbq burgers, smokies, in addition to all the regular bananas, oranges, watermelon, honeydew, granola bars, etc. And there's a beer garden too. And door prizes are always good, but I'm bias, because last year I won the trip for 2 to Tofino with a 2 night stay at the Long Beach Lodge.
A lot of the smaller races have awesome home baked goodies and they're really good. The members of the sponsoring run club bake and bring them to the race. And these smaller races always have reasonable entry fees as well. Because they're smaller, it's not as crowded, and you have a better chance at winning a door prize (or actually placing within your age group!).
If you're looking for road or trail races, here's the local race calenders.
http://www.bcathletics.org/eventcal_rr11.htm
http://www.bcathletics.org/eventcal_xc11.htm
and the Lower Mainland Race series:
http://www.lmrrs.com/
5 Peaks trail running series:
http://www.5peaks.com/schedule.asp?p=bc