I'm teaching in a country where English is the first language, but foreigners come to learn English. I have a choice of books and materials (lucky me) as long as I stick to the syllabus.
In teaching ESL I find that students need to work on all 4 skills. I am fortunate in that I am able to get excellent UK coursebooks which cover Listening, Speaking, Reading and Writing.
Students handle all four skills at elementary, intermediate and advanced levels. The tapes are crucial as they get to listen to English in dialogue situation, diction, stress, consonants, consonant clusters, etc. BBC listening is added to my advanced class.
Each unit gives about 8 hours of lessons and exercises are so varied that there's no chance for the students to be bored.
The accompanying teacher's guide makes teaching a holiday. But I do vary and adapt.
The thing that makes it all work is that I converse in English and not in their languages. That forces them to use English. For the elementary level I speak very slowly, often I have to act it out, and I force them to refer to their bi-lingual dictionary. a bi-lingual dictionary is not encouraged among my advanced level students. They find 'Oxford Advanced Learners' dictionary meets their need.
Beulah

Course books are expensive, for the most part, so I hope the students will get their money's worth! That means that I will be able to use it during each class session, among other things. I look for a book that has the "basics" of whatever we're trying to learn, so that if I have a bad day, or the students are homesick, have a hangover, or are planning how to meet that cute classmate, and are still interested in learning something, they can return to the textbook for self-study. (I have also chosen texts for less-competent teachers for the same basic reason...the essentials are there, no matter what happens in the classroom.)
At present, we are using the same coursebook in two or three sections of the same "level", and we are trying to test on the same day. HOW we get to the test day is our own decision, but it has been a challenge to synchronize with other good teachers. It has also been simpler in some ways as we share supplementary materials that we have or develop, and we can tap background knowledge or experience that may be unique to one of us. I like, too, to have some grammar application activities, as long as they are content-based rather than straight drills. I have students who "know" the rules, but produce the most bizarre constructions.
Rosemary Schmid

I've now been teaching for more than 16 years and I would say I used a course book in a good 12 years of them... There are obviously pros and cons and especially for the lazy teacher, a course book is ideal...but then again, nobody knows your students like you do so supplementing the course book is a must. I love looking at sts' language needs and putting a lesson together from various books...in that way, my lesson is sure to be tailor made to my sts. I normally use a course book as a framework and build around it.
Jean Sciberras

I work at a German Gymnasium (grammar school), where most of my colleagues seem to think the coursebook has been sent by God to save teachers from a fate worse than death. We recently introduced a less old-fashioned course book, but even so I find it a serious constraint to follow the book page for page. So I don't. I make sure all the important structures are covered, and use a mix of the book (with its accompanying listening exercises, some of which are very useful) and other materials. Where to find them? Here and elsewhere on the Web (you can for instance use one of the screenplays available on the internet as a reader and then link it to the video of the film) ; get the pupils to produce grammar dossiers or presentations (they all have laptops, which makes it easier); dig occasionally through the piles of old lessons accumulated over three decades; re-read some of the books on my shelves ... There are no end of things you can do to supplement a coursebook, which will become more and more difficult to use in a motivating way the older it gets. Having one, however, (as long as it's not too disastrous) can be a godsend when your workload is threatening to cause a nervous breakdown!
Bill George

I look for two or three new ideas. Very seldom do I find a fantastic coursebook in which I learn a lot of new things, but if I get new ideas I consider it was worth going. I always attend courses, as many as I can.
Marianne O'Farrell, Argentina.

If grammar is the skeleton then vocabulary is the flesh support this according to the different ways of teaching english and the communicative approach in teaching english as a second language. This is what I look for in a coursebook.
Mehdi