I would pick option number 4, as I dont think exposed skin on Mars is going to fly with OSHA. But short of a discovery or discoveries in material science, life support or drive system, I cant see us getting there without using Buzz Aldrins proposed method.
If not then
Getting there uses the holman transfer method, but takes three years and thats just to get to the planet. Now we gotta have a drop ship to actually get down to the ground and hopefully meet up with some pre positioned supplies, prefab housing, hopefully built by robots or tele operated machines, or even self assembled.
Mine rocket fuel, for the drop ship to return to orbit to meet up with the carrier, weather permitting. To me , that means we have to send an unmanned dropship to Mars, plus the mining/refinery stuff for the fuel, just to see what problems might be associated with that launch.
IF we are gonna do all that, then I cant see going all the way, and not having boots on the ground.