Sometimes I'll cancel immediately after the hit and follow up with a jab+jab+<variations> if they're at the right percents that the hit positions them correctly and/or they don't DI correctly.
But honestly I don't spindash cancel much but for head games or if I'm far enough away that the lag won't get me punished. I'm more likely to either:
1) Hit, turn-around -> jump -> dair (in rapid succession)
2) Hit, jump fair/bair/nair/dair depending on their percent/position based on DI/etc
I will say this about spindash cancel, it can be kind of cool to use it to fall off a ledge. For instance, if your opponent is standing near the ledge, you can spinsash into him, cancel right before getting to the ledge, the screech animation plays for a bit but then you fall off the ledge anyway allowing you to dj back in with a uair/bair.
Edit:
As I think on it a bit more. I'll bet I'm way under-utilizing the spindash cancel. It's lag is stupid long but if you've gotten the hit then the opponent should be equally (or even more) hit-stunned... I'll have to play with it some more and start trying to incorporate it more