El Pueblo is mostly for locals. It is a big complex of night clubs.
Although the characterization of El Pueblo as being for 19 year olds who like ear-popping music and strobe lights is partly correct, it's not just for the K*ds. There is hidden gold in some of the smaller clubs. Take some time to explore, because it is a genuine Costa Rica nightspot, not a tourist trap.
You might hear live Andean music, Argentine Tango by sultry originals from the 60s, salsa, mambo, every style native to Central and South America, depending on what club and what night.
It is about a mile north of central San Jose, probably a bit less as the crow flies. It is just north of the arroyo that passes through the center of San Jose, and is near the an 18th century church, la Iglesia de San Francisco, which would be worth seeing in the daytime.
You can see the Holiday Inn and other downtown landmarks easily from El Pueblo, so you should know exactly where you are, even at night. Ask your cab driver to quote you a fixed fare before you get in the cab. It will depend a lot on what side of downtown you are starting from, and what time of day, since the traffic would be murder if you are on the wrong side of Avenida Central at midday.
Nevada_Doc