When talking about changed plans, don't use "would".

Today someone wanted to tell me that though they had made plans for this afternoon, those plans had changed. They decided not to go where they had planned to go. She said:

× I would go there, but I didn't.
○ I was going to go there, but I didn't.

"Would" is frequently used to describe hypothetical situations, not past situations. You can use "would have" to indicate the past. In that case:

• I would have gone there if I hadn't changed my plans.

However, I think in this case "was going to" is the best choice.

Use "would" to talk about past habits, though:

• When I was a college student, I would drink beer for breakfast.