I own a straight razor, but have never been brave enough to use it on myself.  
You need to be a pretty accomplished blade sharpener in order to keep it as keen as it needs to be.
Just get a Mach 3.  The best self shave you can get.  I've heard some complaints about the triple edge head being a bit thick for some guy's upper lip, but that's pretty minor.  
The key to a good shave is in the preperation.  I always shave at the end of a shower when the humidity has had a chance to soften the whiskers.  I used to use a high quality (and expensive) shaving lotion/soap, but recently I've taken to using a herbal hair conditioner.  Seems to work just as good, and makes my face feel better.  Plus I don't hafta buy two different items now.  Work the lotion in well to help the whiskers stand up away from the face.  Let it sit for a few minutes to soften 'em even more.  Then go to it.  
I typically shave with the grain first and then do a quick run against the grain after I've done my whole face.   If you haven't shaved regularly with a blade, this may be a bit irritating at first.  And some guys are more suseptible to ingrown hairs this way.
For a quick job, I've found that the Remington microscreen triple-blade electrics do shave pretty much just as close as a blade.  Maybe not quite as good as the Mach 3 blade, but better than regular single edge blade.
D