Go for B1/B2. The reasons are

1. It does not take more than what you need from B1
2. With the same cost of application, you are getting B1 and B2
3. In future, if you need to visit the USA for non-business purpose, you will have an advantage of B2
4. It does not harm rather a best possible way to get B2 along with B1

PS: You can not use B1 for tourism purpose. When you travel on B1, you have to carry an invitation from concern parties and business you gonna do in USA.

Hope this helps!

-AG

I would suggest you go for B1/B2. My reasons are:

1. It does not take more than what is required to apply for the B1
2. With the same cost of application, you get both B1 and B2
3. In future, if you need to visit the USA for non-business purpose, you will have the advantage of the B2
4. It's preferable to have the B2 along with the B1

PS: You cannot use B1 for tourism purpose. When you travel on the B1, you have to carry an invitation from the concerned parties and businesses with whom you are going to work in the USA.