Broadly speaking, I want to type in a keyword and find out just what types of search queries people are running that involve that keyword. For example, I'd like to be able to enter "police officer", and find the most common queries involving that keyword / key-phrase; e.g. I'd imagine such a tool would return queries like:

Police officer salary
How much do police officers get paid?
Police officer training
Police officer new york city
etc, etc
(e.g. I'm imagining that those would be common Google searches using my keyword)

The only one I know about at this point is the Google keyword research tool. But any others I should use? Frankly, I've been a little underwhelmed with that keyword research tool (yeah, i know it's free) seems to be somewhat wonky / inconsistent. I want to know where else I can look to see what people are searching for.