Big city with lots on offer
The hop-on, hop-off bus is a good way to figure out what parts of the city you want. If you do hop off in places it'll take two days to do the entire route. Had the best steak ever. The walking tours were good for the history which is interesting. Taxi drivers are crazy. Metro is easy to use and fast to get around. Stick in groups at nighttime as some streets felt a little intimidating.
Insider Tip:Tango lessons at Le Cathedral were my highlight. We arrived at 730 which was on the very early side. Didn't really start picking up till about 9-10. Great food and tango lessons were a blast. Don't let first impressions burst your bubble, grab a bottle of vino and enjoy.