One might say that fear rules the global stock exchanges. Britain was and still is a great country and a leading economic indicator (not being a mere follower) of what we know as western Europe. For countries that cannot compete in terms of GDP, labor population, or sheer magnitude of the economic girth of first world nations; the concept of sharing labor pools (along with labor law restrictions), trade, and distributed wealth (in terms of country-to-country financial loans) seems like a really good idea...that is if the demand for products and services produced by your home country can keep up with all the other countries within that trading region.
In 1998, I took my first trip outside the US; specifically to visit a few countries along the western Caribbean. While food was ridiculously cheap on the eastern coast of Mexico, the same could not be said for the island nations that were still on the British standard of currency. A conch sandwich and a small bowl of turtle soup costed £16 (more than $25 US).
The single biggest benefit to Americans is the rising strength of the US dollar against the British pound and the Euro; effectively making European goods/services cheaper to acquire. The closer we get to a 1:1 ratio, the cheaper it is for Americans to travel to the UK and Britain-managed territories. This isn't limited to travel. Foreign car imports will also be cheaper than they are now. Our domestic automotive dealerships benefit from the weakening Euro in this regard. However, it is still ridiculously expensive to travel from the US to Europe with air fares at more than $1,500/pp one-way.
Something else to consider are the other wealthy European countries that were never part of the EU and continue to flourish such as Norway, Switzerland, Iceland, Turkey, and others.
At the time I wrote this, the currency exchange rate was::
$10 USD = £ 7.57 = € 9.08
In 1998, $10 USD = £ 6.50
In 2008, $10 USD = € 6.50
If you are an infrequent international traveler, you might think to yourself: Meh, what's the big deal with paying a little bit more for the experience, for goods/services that are only available in the visited country, etc.