Upload & Sell: Off
It's a good point. There are really two basic models here. One is Photographer For Hire. The other is Buy My Stuff (prints mainly). There is considerable variety within those two categories, but I am seeing that as the major first decision.
In the for hire sites the images are primarily serving the purpose of a portfolio or demonstration of the product the client may expect. In the Buy My Stuff sites the images are the product.
The for hire sites need limited online shopping cart services, need to emphasize contact info, and seem to have generally more streamlined and pleasing design.
The buy my stuff sites need more complex organization, smooth online purchasing, and may be a little less web design oriented in general.
Both sites seem to benefit from artist statements, blog/article/tips, and other materials that help make the artist real, and offer another way to show off and dicuss/pique-interest-in works.
This has really opened my mind!