I agree with this and given the level of expenses you may have to get more than 1 card anyways. I think I saw in the fine print of AXP that anything over a 50K credit limit and they require audited financial statements.

Besides you might be able to rack up some perks by spreading the spend out over a few cards not to mention diversifying your mileage balances. AXP Gold, Barclays US Air, Chase United Explorer and AXP Delta cards all give bonuses when you hit 25K-30K of spend. You could also rack up status with Delta(with combination of Delta cards) or perhaps at a hotel. As others have said, you would have to look at what your intended use is for any earned points/miles/cash back and then configure your CC portfolio approporiately.