Upvote:4
I would suggest you go for B1/B2. My reasons are:
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.
Upvote:5
As outlined in the statistics in a related question, 97% of all B visas issued by US consulates are B1/B2 visas. Therefore you are likely to receive a B1/B2 visa even if you only apply for a B1 visa.
Personally I would select the B1/B2 option on the DS-160 form - just be prepared to explain what kind of tourist activities you're conceiving in the future. They don't have to be concrete plans, something like "I want to visit NYC next summer" would be sufficient.