There's a wealth of knowledge on these forums and I always enjoy discussing situations with other. 

I host frequent networking events too that you might enjoy.

Every deal is different, and I enjoy being a resource to help investors, landlords, agents, and even builders and developers move forward on their goals.I joined this community to network, share what I’ve learned, and learn from all of you as well.

Not sure how enjoyable a vacant student rental with no furniture would be (assuming you were able to use it)

Is there a personal enjoyment factor? 

I enjoyed the post @Levi Bennett. 

On my side, I work with investors and developers on the funding side — bridge, fix & flip, and construction financing — so I always enjoy connecting with operators who are in the trenches making projects like yours happen.

Guests seem to enjoy it too. 

Those very high returns come from the combination of the very low mortgage interest rates and the steady capital appreciation.Regarding my investment portfolio, I'm still in a growth phase and a phase in which I help an partner with other investors so that they can invest in the most profitable opportunities without having the necessary presence on the ground, time, knowledge and contacts, which is something I really enjoy doing.The biggest hurdle is finding the right opportunities in a hot market, although it's a matter of time, for me at least, so it's not really a hurdle.Legal aspects aren't a hurdle from me because I studied in my native Belgium and have been based in Quebec, both of which have a similar legal system to that of Spain and Portugal (civil law).As to regulations, in Spain, it's a matter of investing in the areas and type of properties that are least affected.

Since this will be a vacation rental that your family wants to enjoy, I would focus on STR for high season & the seasons you want to stay and MTR the rest of the year.