Both films address modern man living in this modern age. Their approach isn't as angsty as Douglas Coupland's (although the Weitzes would do a fine job with Microserfs): more "Well, isn't life just an odd, wacky place" than "Oh, the HORRIBLENESS of it all." (We'll leave the latter kind of films to the French and Michael Moore.) About a Boy is about a man who lives on a metaphorical island and then finds that being connected to other people doesn't totally stink.
In Good Company has a similar theme except that the protagonist, an up and coming sales executive named Carter, lives on a metaphorical island that he wants to get off of and finds it is possible by connecting with other people. In both cases, the Weitz brothers picked actors for their main characters who don't really act so much as act like themselves. Hugh Grant in About a Boy is pretty much playing Hugh Grant, a shallow, rather narcissitic, non-kid loving guy. The raffishness that shows up in Bridget Jones Diary comes through, tempored by an underlying sadness. I prefer Grant in About a Boy, partly because it was perfect casting and partly because I prefer Hugh Grant without the bouncy, wavy, devil-may-care hairdo. In About a Boy, he is pared down, hairwise and clothing wise, to the wiry guy that he is, and it is an elegant wiryness, let me tell you.
Topher Grace is less elegant Hugh Grant, more sincere Tobey Maguire (although Tobey Maguire can be elegant in his own way). But again, Grace basically acts himself; that is, he acts exactly the same way he does on That 70's Show and for his cameo in Ocean's Twelve (he's the guy Brad Pitt visits in the hotel room). He isn't a terribly good actor, but it doesn't really matter since the protagonist is supposed to be this twenty-something corporate ladderman who has lots of energy but is a tad clueless about human nature. And well, there you go.
The problem, therefore, isn't the actors, but the scripts. About a Boy, based on Hornby's novel by the same name, is a great script. It moves, for one thing. In Good Company, I hate to say it, is dull. And I think the reason is this: the Weitzes knew what to say about singlehood, dating and parenting, but they didn't really know what to say about the corporate world. They didn't want to get all down on capitalism since Dennis Quaid is still a salesman at the end of the movie, but their "old style business is better than new style business" argument falls flat since they obviously didn't know what they were talking about. At the end of the movie when the head honcho, Malcolm McDowell shows up and makes his speech about the world getting closer because of shared economics, he is right, and he should have been played as being right. Quaid's character, Dan Foreman, doesn't get it, and although Quaid, with great skill, plays him that way, the script's message is that Foreman is morally better than everyone else and therefore right. He isn't. Nobody gets to be head salesman of a company without firing people and remembering the bottom line. And Carter's decision to protect Foreman should have been based not on Foreman being right but on Carter's desire to protect a man whose lifestyle (wife, kids, house, etc.) he admires. But instead it was played as "Oh, see, old style IS better."
The end result is a movie that dithers, which is too bad, since all the ingredients for success were there. But it's a problem when the most powerful speech in a movie is given by the soulless, corporate guru and the more important so-called "personal elements" just don't come up to scratch.