How to deal with that which uses that and which

Paper or plastic? Ginger or Mary Ann? That or which?

Everyone knows that paper bags are better (unless you use those new cloth bags). Everyone also knows that Mary Ann is far superior to Ginger. Choosing between that and which isn't quite as simple.

But it's not that hard, either.

If you can remove the phrase from the sentence, then you use which. If you can't remove it, you use that.

For instance:

Baseball season is here that/which means Chris will be totally useless until late October.

You can remove the phrase and have Baseball season is here. as a complete sentence. Therefore, which is the appropriate choice.

However:

When baseball season arrives, that/which means Chris will be totally useless until late October.

If you remove the phrase starting with that/which, you have When baseball season arrives, which is not a complete sentence.

The Rule
If the phrase is parenthetical--if you could remove it and still have a complete sentence--use which. Otherwise, use that.

However, if you can remove the that and the sentence makes sense, go for it.