Pass The Mayo, Please. And About That Extra Virgin?

My wife tasked me with finding a recipe for homemade mayonnaise. Something for the upcoming holidays. My first attempt tonight failed on account of the type of oil. I used Trader Joe's Extra Virgin Olive Oil.  To me, it tasted very bitter, just like the oil. What is the best type of oil to use for fresh mayo?

Second, I'm wondering if that batch of olive oil was spoiled. The chemist in me understands how vegetable oils degrade over time. I consulted Hazan, and she specifically says to avoid dark green oils from southern Italy because they are naturally bitter. What are people's thoughts on cooking with and using different grades of olive oils?