One of the first things that struck me upon arriving in Valparaíso, Chile, is its close resemblance to Rio, at least in some obvious ways. It's set on the ocean, its houses climb up the nearby hillsides, the poorer people have the best views, and their neighborhoods are also the most dangerous. Of course, it's much smaller—about the size of Tacoma, or a couple hundred thousand—and is a little mellower (than Rio, at least) in every respect.
Most visitors spend a couple days here, but if you have time, you could probably stretch it almost to a week. First tip: when you arrive, don't take a taxi to your lodging. They're a major rip off. Figure about $12 vs. $1 for a collectivo. Don't ask me how I know this—just take my word for it. In Chile, a collectivo is basically a taxi with a fixed route, and they're cheap (in Argentina, a collectivo is what they call their city buses). The buses in Valparaíso are also cheap and a good way to get around the city. They stop all over creation, not just at predefined stops, as in most cities.
The Yellow House is a nice place to stay and they'll take care of you. It's a Bed & Breakfast and probably not the cheapest place, but I recommend it. Martin, the owner, who is from Australia and who married a Chilena, works with a guy named Michael, who is from Germany and who also married a Chilena. Michael is a guide and he is excellent. His prices are great and he knows his stuff. He'll tell you all kinds of history and interesting facts—stuff you won't otherwise learn. He does a walking tour of the city and also a tour in which he takes you, in his car, to wineries, a fishing village, Pablo Neruda's house, etc. Highly recommended!
Unfortunately, something he told me disappointed me. The city is very colorful, but it got colorful starting only in around 1992, when an American moved here and began to influence the city's direction. I was hoping the color went way back, but alas, it's a modern invention.
I also took the quite-nice electric train to the nearby tourist destination of Viña del Mar. It's basically a smaller city that butts up against Valparaíso—it's roughly in the same bay. Many locals from Santiago—just 120 kilometers to the East—come here for the weekend. If you have extra time, it's worth a half-day visit. Put it at the bottom of your list, though, if you have limited time.
I went to a Tango class here, too, at La Piedra Feliz, on Thursday. It was very nice. Led by an older guy, it lasted two hours, and started out with a bunch of exercises that were meant to help develop the right style of movement for Tango. I really enjoyed that part. Then came the "normal" dancing. I have to admit that Tango is still almost a complete mystery to me. It's difficult for me to know when to start dancing (based on listening to the music) and I hardly know what to do when I start. I'll try to be patient and hope that it will come. I'm learning bits and pieces with each class, but putting it into practice is coming very slowly—kind of like the Spanish! I guess it comes down to time and practice—and patience.
Unfortunately, I was sick the whole time I was here. I got a cold in Mendoza and carried it with me through five days in Valparaíso, on into La Serena (about 7 hours by bus to the north), and all the way up to San Pablo de Atacama (another 16 hours north by bus). I'm on the mend, but still feel sick.