The Pleiospilos does not belong with the others. It needs a deep pot to accommodate the long roots, and it tends to be more active from late summer into wintertime and thus needs to be watered and given as much sun as possible during that time. It will not look good long-term if grown otherwise, instead you will have a plant that just "survives". It should flower every year when healthy.

My plants bloom during the winter or very early spring. After flowering, watering is reduced significantly until late summer when more frequent watering resumes. During the spring and summer new bodies grow as they utilize the moisture from the old leaves. If they are watered too much during this time, the old leaves will not resorb and the plant will not have its characteristic appearance.

Pleiospilos bolusii superficially is similar to P. nelii except that it is much more likely to be a summer grower and is more compatible with the sedums, although I still would not plant them together. The bolusii flower has a wonderful coconut fragrance unlike anything I have ever smelled, it is worth growing just to experience the scent.

I had also read that the P. nelii likes to be planted a little above the surface of the soil. Have you found this to be true with yours? Mine is situated in the deepest section of the pot and with the good drainage it almost seems that I can accomodate somewhat of a zonal watering at this point. I know this may not be the case as and if these guys start growing.
It would be easy to transplant the little guy out.
Considering our winters in the PNW do you think I should invest in an all spectrum light to provide it the light it will need into the winter. I don't know what the weather is like in NYC, but it stays pretty darn gray here in Portland. Thanks for your input and I'll look into the Pleiospilos bolusii. They are all such fascinating plants.

Knowing you are in the PNW helps. Xerophyte's description of P. nelii behaviour might not be the same in your climate. I don't have a good idea where zone 7 is in that area so I won't make any detailed guesses. For example, I water it very lightly and very occasionally all year round but I keep it under lights in winter or it would get no water at all. It flowers each July which is not normal!

Either way, the Pleiospilos is likely to get overwatered in that container with the others. It should be planted with the roots in the soil and the body not in the soil. I generally use a grit top dressing to ensure that the body is not in contact with the soil, because that is asking for rot in a cool damp climate like mine.

The Sempervivum might be happier in a separate container too. They are hardy enough for your winters which none of the others are, they tolerate much more water than the others, and they won't like being baked in full sun at 100F all summer which the Pleiospilos would love :)