Puerto Rico: This isn't technically an independent country; instead, the Commonwealth is a United States territory. English is very common here, but Spanish---in the characteristic Puerto Rican dialect---is the primary language.
Costa Rica: Spanish is the official language, but English is also very common here.
Belize: English is actually the official language, but many residents of Belize are multilingual, and Spanish is commonly spoken; according to census records, in some regions, Spanish is the first language of the majority of citizens.
Brazil: You will find English and Spanish both commonly spoken here, although the official language is Portuguese---close enough to Spanish, in some cases, to be very confusing. Your Spanish would be useful here, but it's not the destination of choice for immersion.
A Dialect Apart
Spain: The castellano or Castilian Spanish dialect is the official language here, with other official languages and dialects distributed regionally. There are some differences in pronunciation between castellano and Latin American Spanish, and some differences in vocabulary and conjugation as well.