Ofc it isn't enough, especially when you want to communicate with ppl of specified culture. But here couldn't be any recommendation as well, it must be only your decision. If want communicate with Spanish folk, then you might chose Spanish, but if want to know Norwegian ppl, then your choice is Norwegian. In fact, it doesn't matter how widely the language is spoken if you want it for fun only. Another thing may be when it comes to your job and then advantage will be determinant and then it can be as well as German, Russian or smth else. But again all depends on your needs.

In my opinion spanish is the best bet. It is very similar to english and easy to learn if you have already mastered english language. It also highly depends on what culture you are interested in. If you know mandarin, english and spanish it means you can speak to like more than a half people who live on this earth.

It al depends on what you want to do with the language. If you want to settle down in a country, you might want to learn that language.