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