B737-800 Captain reported encountering wake turbulence on approach into SEA in trail of an A321.

Narrative

On approach to Seattle; was radar vectored to join the localizer [for Runway] 16R from the west; and given a mandatory descent to 3000 ft. This put us underneath preceding traffic 5 miles ahead; an A-321 which joined the glide slope [Runway] 16R straight in from 4000 ft. With light to non-existent winds in the lower atmosphere; the result was predictable; moderate wake turbulence consisting of several rhythmic jolts followed by several rolls of 20-30 deg bank before I was able to safely maneuver out of the wake. Positioned aircraft about a quarter mile west of localizer and climbed to approximately 3200 ft. to get out of the wake; then had to fly one dot above glide slope to stay out of the Airbus' wake as they were a bit high on their approach. Remainder of approach and landing was normal and uneventful. Submitting this report in case there are any passenger concerns or inquiries. After a smooth flight up the coast from ZZZ; I am sure a few nerves in the back were rattled. I am not sure why ATC needed us to join the localizer at 3000 ft. If given 4000 ft; our ability to avoid the Airbus' wake would have been much improved. Alternatively; the curved path of the RNAV approach to [Runway] 16R would have mitigated our exposure time to wake turbulence. We elected to stay on the instrument approach this flight to mitigate the effects of our fatiguing schedule. In the future will give more consideration to the visual approach; even when fatigued; as a wake turbulence mitigation strategy.