On the topic of "tiers," I have found that with Citibank, when my credit card has a small balance, I get really good phone support. If my card has a medium balance (say, $2,000 to $9,000), I get shoved off to a third-world call center. But when my balance climbs over $20,000, I get the good service again.

Yes, my balance fluctuates wildly month-to-month. Travel.