I am a Chinese living in Madrid, so naturally I learnt Castilian accent of Spain, but when I took the Spanish test Dele especially the part of listening comprehension, I noticed that there are so many different spanish accents that I am not familiar with at all. Since you are northamerican, I guess it is better to learn Mexican Spanish or other Southamerican Spanish, because it is more practical, and there are only a few Spaniards in your country. The accents and dialects are not very important, the comunication is essential. I see many Spanish kids learnt British English in school, but if they go to USA, they can understand American English.