Your first important decision, before you choose a location or a banquet menu, is to define what you want to accomplish with your customer conference. With a clearly defined focus from the start, other decisions are easier to make.
The goal you have for your customer conference depends upon where you are in the life cycle of the company and the product. A startup product or company may be much less concerned with profitability than with building visibility in the industry and developing advocates among your customer base. A more established product might focus on ensuring that users develop a solid knowledge of the product and help set the product direction.
I suggest that as Product Manager, you will have more impact by setting a goal that directly ties your customer conference to a measure of success that the executive team will value. Then, describe the results you are aiming for in order to accomplish that goal, and follow that with the strategies and tactics to attain those results.