I would suggest threading lightly here, lest this turn into an umpteenth thread on status of Catalan and Spanish in Catalonia and all things related. Should you feel inclined to weigh in on that, there are already plenty of threads, for example here, here, here, here and even here; the fate of the last one is what prompted me to write this.
As for the title question, if we are wiling to modified it and ask: to what extent is this or that country/region bilingual? then I would agree with Taraborn that Catalonia is very very bilingual. On the scale of 1-10, with 10 being absolutely bilingual, I give Catalonia a solid 7. Large parts of Ukraine would probably score pretty high as well, with lots of people being proficient in Russian and Ukrainian. I would give Ukraine a 6.
Again we are back into a totally different definition of what at least a lot of people - obviously including myself - would use for "bilingual country", so I am not going to comment on that.