As it currently stands as a non EU citizen your choices are limited.
The 90/180 Schengen shuffle is of course easiest and no paperwork required other that ETIAS when that goes online - simple traveller check system for security purposes and nominal cost for 3 years.
There is a Schengen visa but that is for persons from specific countries that require a pre approved visa before entering Schengen even for short stay , all I read seems to say it is also only for 90 days max.
After Jan 1st 2021 getting caught over staying will be become much more likely - the penalties can be a pain ....
What is not known is "if" there may be something new arising out of the negotiations going forward that would cater to the snow bird crowd and those with second homes in Spain .....
I suspect this question may come up a lot either later this year or most certainly in 2021 when restrictions on being non eu start to bite.
:-(