I used to switch between US and DK layouts, it's just so much easier to just have one layout. In my opinion, learning US Intl is worth it. Besides, it's pretty predictable for Spanish characters: á = altgr+a, é = altgr+e and so on.
Trying to remember more than two layouts becomes confusing very fast. AZERTY and QWERZ are the two worst ones, fortunately I never need to use those.