No matter how well designed your final product turns out to be, it is always hard to dissuade people from predetermined notions of how it should look. Do your best to prevent those who will eventually use your completed dashboard from developing expectations about its look and feel apart from your input and expert advice. Present your users with a single prototype of the most effective design that you can create, and let that be the starting point for discussions about how it might be tweaked to better serve their needs. Don't present them with several alternative designs, because even though your users probably know what they need to accomplish, they don't know how the dashboard ought to be visually designed to achieve that result. You are the designer, so it is up to you to bring this expertise to the process.
You will never get everything right on the first try, no matter how skilled you are. You must put your design to the test. Only those who will actually use the dashboard are qualified to determine if it actually works and works well. Show it to them populated with real data, and observe them as they look it over and learn to make sense of the data. If you are introducing display media that are new to them, begin with simple instruction in how they work and explain why you chose those mechanisms rather than others that might be more familiar. If you've done your homework and your users really care about doing their jobs well rather than doing them in a particular way, usability testing will usually result in relatively minor additions and tweaks to refine the effectiveness of the dashboard, rather than major revisions. Although there are certainly exceptions when dealing with the foibles of human beings, good design usually results in a good reception.