Would it reduce the cost/time to go to Mars with people if the transit vehicle was accelerated using less expensive means (i.e. ion engine and/or gravity assists), and the people got took a small quick vehicle to catch up?
More detailed example: Launch the transit vehicle (the space ship that will go to Mars) long before the people will actually start their voyage. Then use slow acceleration techniques (i.e. ion thruster and/or gravity assists) to speed up the transit vehicle. When the transit vehicle is going fast enough, send the people up in a small, quick craft to get on the transit vehicle.
If the transit vehicle stayed orbiting Earth, presumably it would have to be in an elliptical orbit. If the transit vehicle used gravity assists, presumably it could get much faster speeds than an elliptical orbit could produce and it would be harder to get the timing correct for the transit vehicle to pass Earth on its way to Mars.