I taught a company class for a year, it depended on the day as to how many I had per class. Obviously it depends on the personalities you get attending, but the guys I taught loved to have discussion games to break up the monotony of going over grammar and structure. As LivinginKorea says there are a lot of good activity based books for business students and also a lot of resource on the internet. I used a lot of stuff from iteslj.org for conversation based lessons, also
www.breakingnewsenglish.com is good as each lesson gives you an idea of how to incorporate grammar exercises as well as some free thinking group/pair work.
Here's a good exercise that the instructor on my training course made us do and would be good for practising opinions & debating. You need a good group of between 10-20. Give the class a subject -eg Things to take on holiday and in pairs they they have to come up with 6 essential items that they would take with them. Once they have done this then regroup everyone, divide them into groups of 3 and get them to discuss the lists they have made already and whittle the number of items down to 4. (you can jig around with the numbers as it suits). Once this is done you then regroup them in 4's and the number on their list has to come down to 3 items.
You can go on as long as necessary but the idea is to move the students into different discussion groups and get them to defend and argue for their choices to be included on the list.
(Hope that made sense as it is a very good activity that involves hardly any teacher talking and gets them debating) It's interesting to compare the lists at the end and to see how similar, or not, they are.
xx