I have found it really helpful to work with themes. As your students are in the same company, there are probably common themes that would be relevant to them. You could create a list of possible themes (perhaps with student input), and you could either choose which of these to use with particular students, or they could choose which are most useful to them.
When you've chosen your themes, you can then look at relevant vocabulary, grammar and functions that would work in that unit. You can use the same theme with low beginners to upper advanced, but you can choose different grammatical features, vocabulary etc. to focus on.
Another nice thing about this approach is that you start to develop a good resource bank that you can use with new students, and you don't feel that you always have to create new materials.
You can find some resources online about the specifics of developing thematic units and syllabi.
I hope this is useful! Feel free to pm me if you want if you have trouble finding resources for developing theme units.