While I *hope* the OP collects a zillion FF miles, he should go in with the expectations that the airline miles game is substantially less rewarding than it once was. You usually have to fly farther and on higher fares to earn status, and the total redeemable miles coming back to you is generally less than it once was. Different airlines have different mechanics for limiting the RDMs you receive: U.S. carriers have gone to revenue multipliers; many non-U.S. carriers have gone to gradually moving more and more common coach fares into fractional-earning categories. Bonuses-upon-bonuses are mostly a thing of the past. Route bonuses are rare; booking bonuses are mostly gone, etc. Airline miles have become a big credit card game in some parts of the world, although I'm not sure what that landscape is like in Spain.

Even in business class, there are more and more discounted fare buckets that don't earn what full-J once did.

The hotel game is still pretty lucrative with stackable bonuses in play. 2017-2018 are volatile years with the big HHonors and Hyatt devaluations earlier this year and the Marriott/Starwood unknowns ahead. But I still like what I get from these programs. My HHonors stay last week earned 52 points per dollar thanks to a variety of bonuses, and I'll redeem those points this summer at just under 1 cent per point. So that's still not too bad...