Rotterdam is the second largest city in the Netherlands after Amsterdam, but it's barely a blip on the overall travel scene next to its more famous neighbor 80 km to the north. But that's not to say Rotterdam doesn't have a charm of its own.
What to do
A visit to Rotterdam is a great way to experience the pleasant day-to-day life of the urban Dutch without having to fight your way through throngs of package tourists streaming from one tourist trap to the next. The city center was obliterated in World War II so there isn't much in the way of historical architecture to enjoy, but in its place you can see great examples of modern design, all centered along a pedestrian street that set the trend for such car-free thoroughfares throughout Europe.
Rotterdam's harbor was recently surpassed by Shanghai as the largest in the world. You can take a harbor tour or visit some historic ships docked there, but the harbor is mostly industrial in nature. Rotterdam has its share of great museums, notably the excellent Museum Boijmans Van Beuningen, which features four distinct sections and is filled with art by the European greats.
If you are looking for an alternative to Amsterdam, or just a side-trip, you needn't worry about missing out on the soft drugs that make the Netherlands such a draw for those interested in them. Rotterdam has Amsterdam-style coffee shops all over town, although there are fewer of them and they tend to cater to locals more than fresh-off-the-plane college students.
Flights into Rotterdam are possible from nearby cities, but not for long haul flights. The small airport might come in handy from within Europe and particularly on some of the new low cost carriers that offer low fares by using regional airports, but most people will find the best deals by flying into Amsterdam. From there you can hop on a train right beneath the airport and be in Rotterdam in under an hour.
Where to stay
Rotterdam has quite a few hostels to choose from, notably one called The Clipper that is a boat docked on a central located in the old harbor. There are quite a few Rotterdam hotels to choose from as well, but as with everywhere they can fill up fast during busy periods.