Fodor's Travel Talk Forums - schengen visa with combine itinerary and multiple dates

I am planning to apply for schengen visa. I am legally resident in Ireland and from Non-EU country and I need visa to travel to schengen country. Last time when I applied for schengen visa, I received visa only for the duration of my itinerary (10 days) based on my itinerary.
Now again I am planning to apply this year. This time I want for longer duration say like 2 months so that I can travel multiple times during that interval. Can I show two different itinerary, one for July and one for August? Can somebody who has done similar things give some ideas so that I can get visa for longer duration.