With the caveat that I have no particular qualifications in linguistics or English grammar: Actually I think that example would be better as: "if you have ever had the opportunity to go to Europe, I'm sure you will have thought about visiting Spain". To imply that the condition was not met or was probably not met (a remoter likelihood): "if you had ever had the opportunity to go to Europe, I'm sure you would've thought about visiting Spain". The construction "if" + present perfect is relatively neutral as to the likelihood of the condition being met. Thus: "I'm going to check on your bedroom now, and if you have tidied it properly, you'll be having ice-cream for afters. But if not, you'll be going to bed without any supper!" [I do not approve of that parenting style!!] In that example about the bedroom, the parent/speaker is not implying any particular likelihood that the child will have tidied their bedroom - it may or may not have happened. Or: "If you have finished your homework, it would be great to hear your conclusions." In the homework example, "it would be great" probably implies a further if-condition not expressly stated, e.g. "If you have finished your homework, then, if you would like to tell me your conclusions, it would be great to hear them". The sentence does not mean that the speaker necessarily expects to hear the conclusions if the other person has finished their homework - rather, the speaker is leaving that person a choice. This double-conditionality, I think, permits the seeming mis-match in tense between "if you have" and "it would be" - it is not really a mis-match, because the stated if-conditions are not comprehensive (i.e. the stated conditions are necessary but not sufficient for the stated outcome).

Svitlana, your sentence is correct but not especially clear. What is it trying to say? Does it talk about people who have gone to Europe, or merely those who could have gone there? Does it talk about going in addition to Spain when the person was in Europe, or as an afterthought after returning home? Does it talk only about thoughts or is also about travel. Again, there's nothing erroneous with the sentence, it's just wishy-washy. All I can conclude from it is that people who have thought about Europe have surely also thought about Spain. Since Spain is part of Europe, that really doesn't say much.

You have you tenses mixed. For third conditional, you need “If you ever had had the opportunity…”. Past perfect then past conditional. If you want to use “if you ever had”, you need to finish with “you could/should think about visiting”. This is second conditional. Past then conditional.