As a side note, my girl friend just went back to school last year at 29 to attempt a new degree as she want to try something totally different as well. She finds it a little more difficult that when she was in school 8-10 years ago. She is really enjoying the experience and has chosen a major that she likes instead of one that her parents thought would be good for her. She has also noted that there are a lot of people in her classes her age and older getting a first or second degree.

Therefore, a concentration in another area–even if it’s a new area for you–would dictate that you do so in a graduate program. It doesn’t matter if you’re taking a graduate program in engineering and had a bachelor’s in English. Nobody will care, and the courses you’d take as background would mostly count as graduate credit, though some might not; it depends on your particular program.

But you are a prime candidate for a master’s program; that’s why they’re offered. You’ll also find that the requirements for the master’s are whatever your advisor says that they are, so you can customize your program more easily than as an undergraduate.