Multi-SIM phones are all fine and dandy, but they have their limits: you rarely get more than two lines, and they may be overkill if you just want a new set of digits rather than a wholly separate connection. Verizon (Engadget's parent company) thinks it has a fix. The carrier has launched a My Numbers app for Android and iOS that puts as many as four extra numbers on your phone. You can divide them by personal and work lines, and use them for unlimited domestic calling and texting.
In some ways, though, the pricing is the hook. You can add lines for $15 each. That's not trivial, but easier to justify than a full line. Be aware of the catches, though. This won't help if you want service on another carrier (for backup or better rates, as an example). And if you decide to switch carriers, you'll have a headache on your hands trying to move those lines over -- yes, it's a classic case of lock-in. However, this might be helpful if you want a separate work line with relatively little fuss.