I just returned from a week at Cerro Tololo InterAmerican Observatory, better known as CTIO. The primary reason for the trip was to install and test APASS, but mountain observatories are fun for many reasons!
I was picked up at the La Serena airport by a CTIO driver in an SUV. You take a left out of the airport, follow the paved road for a half hour past lots of Chilean grape and fruit orchards, and then turn onto the dirt road that leads up to CTIO. The unpaved portion is quite long, leading up through a desert valley with the principal vegetation being cactus. After 45 minutes, you reach a junction, where one road goes to El Pachon (where Gemini-South and SOAR reside, and where LSST will be sited in the near future), and the other road goes to CTIO.
Astronomers end up in the "dorm", 11 rooms adjacent to the cafeteria. There are also a few "houses" with multiple bedrooms that can be rented for teams or larger groups. The cafeteria handles both the visiting astronomers as well as the day-time support staff. You get three meals per day, and can also request sandwiches, coffee, etc. for a "night lunch". The cafeteria building remains open 24/7, so that you can get some basic items like coffee, tea, milk, juice, cereal, leftover desserts, etc. in addition to your night lunch.
My typical day would be to wake up, have breakfast, and work on APASS in the morning. After lunch, Tom Smith and I might work a bit more on APASS, depending on what needed to be done. More typically, the afternoons are free for most astronomers, and they read, check email, go for hikes, etc. After dinner (5-7pm), most of the visiting astronomers head up to the 4m parking lot on top of the mountain to watch sunset. The mountains all stand out in bold relief with the shadows; you can watch the shadow of Cerro Tololo march across the hills to the east. The sunset itself occurs over the ocean, and quite often you can see a green flash.
After sunset, you head back to your telescope of choice, take flats, and prepare for the night-time observing. With APASS, we were taking pretty pictures, checking focus, doing a pointing model, creating flats, etc. at the beginning, but towards the end, just watched as the ACP Scheduler took control of the telescope and started the night's observing. If you are on one of the other telescopes, like the 0.9m, you would remain up all night doing your observing. Tom and I usually went back to the dorms about 11pm and got some sleep!
The vegetation at CTIO is typical desert - small plants, a few bushes, some cactus. This is late spring in Chile, so there were a number of wildflowers. There are foxes (Zorros) that would hang out near the cafeteria, and an interesting creature called a Vizcacha which is like a cross between a squirrel and a jackrabbit. They watched the sunset too! There are lots of birds, including a burrowing parrot at lower elevations and condors at the mountain top. You always bring a camera when observing so that you can document these creatures and plants.
If you could wake up early in the morning, you can look from CTIO and see the marine layer clouds below you, filling the valleys. The evening meal at CTIO is usually fun. You get to talk to the other visiting astronomers, and they come from all fields and all universities. Some are senior researchers; others are visiting high school kids accompanying a younger researcher. They always grumble about the seeing, clouds, or equipment malfunctions, but the general attitude is a strong motivation to get their research observing finished!
APASS occupies one of the 6 PROMPT clamshells; the other 5 contain 40cm RCOS telescopes on Paramounts. Two of the Univ. North Carolina PROMPT team were at CTIO with us, doing annual maintenance on their robotic telescopes. I actually hand-carried some repair parts to CTIO for them. They both had better cameras than we did, and one of them has posted some of their photos at http://picasaweb.google.com/jhaislip/Chile2010 
All-in-all, it was a pretty typical engineering run at a professional observatory. If you ever get a chance to see some of the Chilean observatories, be sure to take that opportunity!