|It might work either way|
Okay, let's be realistic here: sunsets are made for color images. I'm willing to bet even Ansel Adams, a master of monochrome, found out about the new color films and said, "Holy shit, I gotta try that out on a sunset!" (exact words, no doubt.)
But with the right range of light levels, they can work in black & white too. In a lot of cases, our moods are dictated by color, and depending on what is captured during sunset or sunrise, you can evoke positive feelings from people just from the color registers that are captured. In monochrome, things tend to become starker and moodier – more expressive of a storm perhaps, where the light colors become muted, or perhaps just reminiscent of times past that we automatically associate with B&W since that's the only way images were captured then. And I think more attention is drawn to the crepuscular rays, the beams across the sky, that carry us to the horizon and give a strong sense of depth to the image.
I have two versions, and they were accomplished in different ways. The one at top was simply converted to monochrome. The one at left, taken less than a minute later from a higher floor of the condo we were staying at, is only the red channel, which produced the brighter highlights from the sun area. Without that, there was almost nothing in the frame that approached the upper end of the exposure levels, no "whites" in other words (even though there were practically no whites in the frame to begin with, the red channel reached maximum levels near the sun and thus, when only that channel was used, those levels came out white.) You can decide which one you like best, but it's a good demonstration of the differences the approach can make.
Both images, I should add, were under-exposed from the recommendations of the camera's exposure meter by 1 1/3 stop – I always recommend heavy exposure bracketing during sunrise and sunset shots, but typically, the best colors come out with under-exposure. These were taken during a week-long trip to North Topsail Beach in NC, a trip with excellent weather that resulted in adding – are you ready for this? – 464 images to my sunrise/sunset stock folder alone! Granted, a lot of them are sequential frames intended to capture subtle differences, but it's safe to say I have a wide variety of sunrise and sunset photos from the trip.