I have US and Spanish passports, and have previously held and am eligible to get a French passport. I keep it simple, one US and one EU- the EU passport being the easiest one to get depending on where I'm living. Since there's a Spanish Consulate in San Juan, it's a no-brainer.

I might also qualify for an Israeli and Guatemalan passports, but I haven't bothered trying since neither one offers me anything I need at the moment.