In addition, you can dig into the paid side of search and find out what keywords your competitors are bidding on, and then leverage those keywords for your own organic benefit if you're not already doing so. Search Metrics does this as well, but I've found SEMRush to provide a greater range of keywords and they save more historical keyword data than Search Metrics.
Scout is an easy to use extension tool for chrome browsers that turns your website into a significant keyword generator. By a click of mouse, you can uncover relevant keywords in your industry by choosing a website that is successful and attractive to your audience. You will be able to understand the true language of your successful audience and generate keyword ideas that you can use in your marketing strategy.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.