Once you know the commands, it's very versatile. but it's very airline specific..
If you work for an AMR company there's Griffs guide
http://www.talkairline.com/showthread.php?372-Griff-s-SABRE-Guide
otherwise the schoolhouse will sell you a DECs manual for a few dollars.
NS to get aircraft tail number assigned to your flight (and crew information to SABRE-stalk your other crew members)
JPD to look at the dispatch release
RGMN to look at the MELs on the aircraft
KVA to look at the open writeups
that way when you get physical access to the aircraft and the aircraft logbook, you are already aware of what should be in the logbook and if things aren't right.
FL to see ACARs messages and time stamps between soc and the aircraft , i.e. To get the time stamp when you sent the aircraft fuel to load planning to prove that you didn't cause the delay. Or that you didn't time travel by messing with the reported out and in times.
However I think you probably have access to the mobile CCI app on your smartphone (download from the company website) which allows you to access all the same information without needing to type in all the archaic commands.
The best commands were for swapping trips and picking up trips right when open time opens. You preload the commands to F keys, so that as soon as it opens you just press F1/F2/F3 or whatever key you saved them and get 8 trip trade requests in and approved in less than 0.5 seconds - it's faster than typing all the commands in manually - you can't do that using a mouse point and click interface like FLICA.
The more important one is RES access if you're a commuter....
XI, ET, ET made the pilots that are senior to you for the jumpseat disappear off the standby list giving you the jumpseat.... (just kidding - it does do this but it was more a fantasy - you'd probably get fired if you actually did this as everything is time stamped with your login)
More useful use of RES access is to see if jumpseaters are listed for the flight you're working and you can keep tabs on them while you're in the cockpit getting preflight duties done to see they got taken care of and the gate agent isn't ignoring them. I.e. they're assigned a seat or they're still waiting for a seat or they're in the cockpit jumpseat. Or it's time to go up to the gate to intervene for the jumpseater.
Or conversely if the jumpseater was a troublemaker or gave your flight attendants a hard time or didn't stop by the flight deck, you could access their full name, employee number, date of birth, date of hire and airline they work for.