CUSTOMER PRIORITIZING

Should a $1,000,000 + a year customer be treated differently than say a $10,000,000 + year customer? Should you show them less gratitude, give them less than marketable product? What point do you draw the line at? And if you do draw the line, what about those customers who only spend $100,000 a year? Do you treat them REALLY crappy? Personally I don't feel that ANY customer should be treated any differently because of their amount of purchase,they are still purchases,That you would not have otherwise and more times than not, your profit margin on the $1,000,000 a year or $100,000 a year guy is more than the $10,000,000 a year guy? I would love to hear what you think on this matter.