Spanish is the default foreign language to study in California (where I grew up). I think it is a good first foreign language for anybody in the United States to pick up. Even a little bit of Spanish knowledge (e.g. basic pronunciation) can go a long way! Learning a little bit of Spanish today will offer you compounding rewards over time if you keep your eyes and ears open.
Topical pages on Spanish language topics authored by me,
Spanish is a pluricentric language, meaning it has many "centers" from which users base standard speaking/writing. Pretty much all popular things translated into English are also translated into Spanish, so Spanish is a useful "global" (c.f. "Western European") language to learn. This usefulness has allowed Spanish to continue the conquista of the Americas.
Spanish has many, many speakers. Nonetheless, on the Internet, it is mostly used on US-owned mega-websites like Facebook and Google.
English and Spanish are not readily mutually intelligible, meaning you can't just understand Spanish (to any sophisticated degree) without specialized training. Learning Spanish is therefore a useful thing to do if you plan on spending a lot of time with Spanish monolinguals.