I think a good list would be ordered by the total volume in sales that company / site does.  Not Bitcoin sales, but total sales.  This gives you a feel of how "big" the company is or how much "stuff" they sell.

In that regard
Amazon $88 billion / yr
Dell - $57 billion / yr
EBay - $17 billion / yr
Starbucks - $16 billion / yr
Overstock - 1.5 billion
.
.
.
BitPremier - 0.001 billion / yr