HD 209458 b
If the Gliese 667C system is like visiting New York City, HD 209458 b is like visiting Rome. It's hard to overstate the importance of this planet's contributions to extrasolar research. It was the first transiting planet discovered, the first exoplanet with a confirmed atmosphere, and the guinea pig for measuring orbital speed and extrasolar super-storms. This planet collects milestones like they're pennies. And while it's one of those "hot Jupiter" hell worlds, the good news is that it gushes water vapor all over the place, so you're not going to get dehydrated as you boil to death.
What to bring: Sandals; popsicles; reverence.