Another approach you can use, but very sparingly, is to take a position on something that you know is on the opposite side of what you know Super Busy/ super smart Person A takes. For this to work, you must do your homework and present reasonably good contra arguments. Often times, these type A people cannot resist showing off and will stay up all night putting together awesome research "proving you wrong". Thank them politely for helping you and use all the information they just graciously provided. Again, sparingly, and you must do your homework, you have to be careful, be sure to acknowledge their contribution.