One of my best friends is a berry farmer, so I asked. Here's what he said...
Unless you're keeping the berries for jam or smoothies or such, less than a year for rasps and maybe a little longer for blackberries (which maintain their integrity better).
Commercially-frozen berries in the opaque bags are almost always damaged goods before you get them. Berries carefully home-frozen on a cookie sheet and stored in rigid containers last longer.
Blueberries seem to last much longer.