When cooking with it, it doesn't really matter which we have. We do usually go for extra virgin as we're happy with the strong taste (even for fried eggs) and it depends on what deals are available. For standard extra-virgin oils, more-expensive doesn't equate to better - occasionally a supermarket has a 2-4-1 deal and we stock up, or a local Greek or Turkish shop will have some nice ones on offer, even the Lidl (discount supermarket) has well priced good oil.

We only get snobby on the oil we eat cold - salads, dipped in bread, vegetable marinades for antipesto etc...

I grew up eating a lot of local agricultural produce from Spain and have had a hand in harvesting and pressing oil (both in Spain and in Italy).

Good oils, from Spain, Italy, Greece, Turkey, Moroccan, Australia etc... will vary. They vary considerably depending on the 'farm' and the pressing process used. If it's done with love and care and the olives are good quality, it doesn't really matter to me where they come from (although it is natural that I'll sway towards Spain).

Most important thing is the date of a good oil. The newer, the better. Oil in no way improves with age. I'd advise always to check the dates on the bottle. Oils should get thicker in cool weather, and a bit of sediment is usually a good thing.

An OK oil can be pepped up by popping a dried chilli into a bottle and leaving it to marinade for a while. I think some less honest oil producers do this to some of their oils to give it some of the 'pepperiness' that is currently in demand. The effect can be subtle and not taste obviously of chilli. But, depending on your tastes, even a really good oil can be given an extra edge this way.

The Moroccans like to very gently cook chillis in olive oil and serve it with bread and a little salt. This can be quite sensational.

I doubt I'll even get to taste even a fraction of what is available in my life time though. Same with olives themselves. There must be thousands of ways of preparing them, there was a time when every household in Spain would have had their own method, my grandad's were amazing and his son still makes his own with self-gathered mountain herbs. As a cottage industry, it's not as common as it once was, but a significant amount of Spaniards still have their own personal recipes and supplies.