Sorry to resurrect a long dead forum, but I found the discussion informative in places... and full of misinformation in others. In any case, I have a perspective that hasn't been mentioned as yet.
The reason that towns and cities don't sealcoat is that they REPAVE every so often, and sealcoating makes that problematic. With a driveway, you're not seeing anywhere near the level of traffic that a road has, so the goal is to make it last as long as possible.
I live up North where we see deep ground freezing every year. This makes a HUGE difference in the way we maintain driveways. Down south, a sealcoat may well be relatively useless except as a cosmetic treatment. Up north, most of us sealcoat... and we do it every few years at least.
If we don't seal, water seeps into cracks and then causes frost heaving. A non-coated driveway lasts about a quarter as long as one that is maintained (cracks filled and surface sealed on a regular basis). Depending on drainage, grade and other factors, a well maintained driveway can last more than 20 years. In stark contrast, I've seen poorly maintained driveways disintegrate in 5 years or less. Another factor up north is that once a driveway starts to see frost heaving, it becomes non-planar and plows will tear it to hell adding to the problem.
Also, no matter what the 'pros' say, there is ZERO difference between 'professional' coating and store bought coatings except cost. In northern climates, they ALL get beat up over the course of a few years. therefore, the goal is to plan on redoing it as needed to maintain a waterproof surface.
