Train myself in all the sciences, especially engineering and all kinds of power generation. Once I'd amassed enough knowledge, I think I'd learn to fly a jet. If, that is, I could keep a military base / sim complex powered up long enough to use the simulators.
After that, I'd get one of those new SuperBoeings (the one with a gym
and a bar
inside) and fill it with food and seed stock. Then I'd find somewhere sunny and build a solar farm. Either that or find somewhere that runs of a geothermal power station and make that my base. Power problem: sorted. Just because civilisation has gone to toast doesn't mean that I'll tolerate cold showers.
Once finished I'd scavenge for a wide a variety of nonperishable foodstuffs as possible and repeat the operation on other continents. Once I've got a base on all the major landmasses (I'd say that'd take me fifteen years or so - the first one would be the hardest) I'd go exploring. I would, of course, explore and then seal off anything important like the Natural History Musuem, the Smithsonian, every national library and various other places, and then leave nuclear - decay - powered radio beacons (built with the experience that would have come from starting up and running a nuclear power plant at some point.
I'd have to do a certain amount of scavenging as these supply bases would be too far away from each other initally, but I suppose I'd set up caches of stuff here and there all over the place. Either that or pillage. Arming oneself would be important - so a sniper rifle and some subweapons would be essential. I wouldn't plan on letting any hungry animal get close to me unless on my terms, plus I'd be reduced to a meat and veg diet. No refined stuff unless I find a Cadbury's factory. (Mmm)
After that, (and assuming by this time that I'm middle-aged - these things take time), I'd either just travel and take lots of cameras along with me and record everything in pictures or find and drive every fast car that I've ever wanted to drive. (I'd have clean petrol stocks with me in a bus somewhere. I'm assuming that I can get a bus onto a plane somehow).
Something rather morbid, though. What happens when it's your time to die? Would you dig your own grave or just keel over somewhere and rot? (Assuming of course that you don't screw something up and somehow blow yourself to bits in the preceeding years).
Well before that, though, I'd have started keeping cats with me. Hundreds of the things. I'd probably go insane long before I got all this done though.