Lee and I use a standard photoshelter account linked to a wordpress blog. Contrary to other views, I find the SEO for the blog to be amazing. The secret appears to be putting good tags on each post. I often find our site on the first page of google only an hour or two after putting a post up.
The main reason we use photoshelter is because it offers excellent facilities to get pics to clients and editors, and also because it provides good instant fulfilment of jpegs as well. For printing I usually use my Smugmug site to take orders for event pics using PayPal.
If you want a look to compare, my Smugmug is
www.tobinators.com and the wordpress/photoshelter is
http://slikimages.com.