Vibrant, young city. Just three hours from buenos aires by car, you will find a really nice city with a lot of parks and green spots, nightlife, restaurants and a piece of argentine history because of some great monuments, flag monument being the most important one.
I accidentally ended up spending two weeks in Rosario instead of Buenos Aires, and I completely fell in love with it. Plus, a great Spanish school (Spanish in Rosario) kept me busy and getting to know the local culture. The third largest city in Argentina (pop 1.3mil), the city isn't the most attractive on first glance. The streets can be dirty, there's lots of exhaust pollution, and some of the Soviet-style apartment buildings are downright depressing. But then you peel away the layers and fin gorgeous colonial-style homes, a 15-km-long costanera playground along the Paraná River, a nearby river island with a dozen laid-back Caribbean-style beach clubs. If you want to study in Argentina without the hassle and expense of Buenos Aires (and where you can spend a week not encountering a single English speaker), consider Rosario. There's a great local art scene, and coming across a tango milonga or breakdancing competition on the costanera on a warm Sunday evening can't be beat.
I loved Rosario compared to Buenos Aires. It was a great city to just walk around and can also be walked around in at night. There is a lot to do, including enjoy art, enjoy the markets, shopping, looking at the architecture, enjoy the beaches, sit and eat some good food. The only draw back I can say about Rosario... the hungry mosquitos.
After visiting a lot of cities in South America, I finally found it! Rosario is the place to live. No, it's not as glamorous as BA, but compensates it with a total unique culture and atmosphere, similar to BA, different at the same time and captivating. When you spend one day in Rosario, you feel it "I could live here". Meet with locals at Fenicia after sunset for local made beer. Spend an afternoon strolling the 10 Km shore or "costanera", full of parks, local artists, young kissing couples, culture and "mates". Walk around downtown and discover all those cafes, bars, small theaters and street artists. This is not staged for tourists (you actually won't see many around). Women are breathtaking, man are casual, stylish and seductive. As you spend more time in Rosario, you'll feel your heart bitting and your soul complete and you might not want to ever leave.