We had an old pad removed a couple of years ago, and we hired it out. I’ve used jack hammers before for small jobs, but nothing bigger than 50 sq ft. They work great, but require some muscle. And don’t forget about removing the concrete. Concrete weighs about 50 pounds for a 1′ x 1′ x 4″ section. It adds up, and you probably won’t be hauling it away in a half ton ziptruck. Even Bagster max’s out at 3300 lbs, so only ~70 sq ft of a 4″ pad or ~140 sq ft for a 2″ pad.
Check out DCRA’s river smart program. http://green.dc.gov/riversmarthomes Its a program to help reduce storm water runoff, so if your going to put grass, mulch, garden, or pavers (pervious) in place of the driveway, they will give you some advise on what to do, and even offer some rebates to offset the cost. I met with them about adding rain barrels, the pervious paver rebate, and a few other things the other week. Very helpful. Register or call them. http://green.dc.gov/service/becoming-riversmart-homeowner