I would look for a variety of leaf shapes, for that aspect of interest, and something trailing. From there, if you pick several basically different colors, even if they're a bit faded, they will still be different colors, like red, yellow & lime. They might not develop wild multi colors, but should still be a collection of different colors. I haven't encountered any Coleus that couldn't take full sun or none, but compared to the available varieties, the few dozen I've had at various times is barely a drop in the bucket.
I haven't grown any Coleus from seed except for some volunteers that have come up occasionally. Can't say much about the seed aspect.
The ones with "sun", "Florida", will probably look the most faded compared to the pics you find. But all Coleus look different, depending on the amount of sun. If you browse pics in the plant database on this website, you'll see many pics for some of the cultivars, showing a range of appearance from shade to sun.
If you decide to add some blooms, I recommend very light colors. They show up so much better in the shade.
