Can't possibly make any plant suggestions unless we know where you are located. What may grow well in Oregon may not grow equally well in Michigan. Dimensions of planting area would be helpful also.

Good point! I’m right outside New York City. Planting area is about 6’ x 3’

Disclaimer: I love rhododenrons. Could you plant some lower things to fill in under it and trim the dead branches off the rhodie?

Nothing is going to look better than the rhodo in that spot.

Hydrangea would be nice.

I'd use Geranium macrorrhizum--a groundcover. It will look better than any shrub in a small area like that.

I'm not sure Geranium macrorrhizum would thrive there as it needs sunlight, but it would look nice there. I would leave the Rhody alone and plant a shade loving groundcover around it; Vinca minor would be a carefree choice. You could also plant a variety of shade plants, or simply fill in the area with more hosta. Removing the lower limbs and dead limbs from the Rhody would make it look better, IMO.

Year-round dense green is available from boxwood in your shady area.

G. maccrorrhizum is absolutely a plant for shade, and that area is "bright" shade, not dense dark shade. Another plant that would work is Carex flaccosperma, Both are evergreen.

Check out Camellia japonica & Chinese Ginger:

Camellia sasanqua October Magic 'Ruby'. It can be maintained low and compact. And then plant some evergreen ferns (like Holly fern) or perhaps variegated Pachysandra around it for contrast.