And you had nothing but air between you and the hotel, right? Plus, their system may have had a much better antenna system. Your house, no doubt, has numerous walls with many metallic items, from wiring to heat/AC duct work. Not to mention a few items using the exact frequencies of the Extreme/Expresses. And the design of those Apple products have a noticeable lack of such ugly things as external antennae. There are reasons why most radio frequency products have those things, even if it's just using the cord on a set of ear phones as the antenna. The Extreme/Express/mini/MBP/even your iMac have the antennae well hidden and usually BEHIND some metal. DOH! The signal strength is limited by Federal regulation, it can be increased, but not legally (you may remember the interference caused by the poorly controlled CB radio fad?). I wouldn't be surprised to learn that the hotel is operating outside the limits of the law.
Obviously, environmental conditions in one house/office/hotel can be much different in another location. There are also several channels (frequencies) available on most of these transmitters to help prevent your neighbors from interfering with your hardware.
As I recall, your problem was improved (solved?) by
removing an Express, not adding one... I discussed the theory of how and where to locate 'repeaters' in the thread you had back then. There are also, I think, some links to the details by people who know way more than I do (not a small number, BTW!).
The product Pogue used is not expensive. Buy one and see if it helps, when used and set up as the instructions say. If it helps, you've made a good investment. If it doesn't, you've just proved, again, that we should not rely on anecdotal evidence too much.
