Bermuda... a postal box. Maybe even an address shared with other multinationals...
Our real corporate taxes aren't that high, the nominal tax is higher than average, but the average tax paid is lower than average. It's like college tuition, the list price is $50,000 but the average paid is $24,000 (numbers pulled out of my ... but you can see both these numbers in the US News college book). Or hospital pricing, "That'll be $50,000 but we'll take $5,000 from the insurance company and $1,000 from you." Of course corporate tax rates vary by industry, Congressional campaign contributions, accounting cleverness/dishonesty, etc. (I'm personally all for lower corporate tax rates -- if we clean up all the loopholes. Unfortunately, those who campaign on lower corporate taxes also believe that eliminating any loophole is a "back door tax hike." Apparently doing both at the same time is unacceptable, but I think it would be a lot more fair and save money all 'round if we did a revenue-neutral corporate tax cut/loophole elimination.)
Anyway, since yes, we are racing to the bottom, I'm thinking the Netherlands might be too grand, when the Cayman Islands are beckoning. It's not like you need any actual employees at your headquarters.