This is how my site works and it works well. In theory I might be able to make a bit more via an ad network, but I like treating my site like a magazine and have highly relevant and high-quality ads.
Two questions: how much time do you spend selling/negotiating with advertisers? And you say you could earn more from a network: have you researched at all exactly how much more?
Naively, it seems that maybe advertisers would pay you more because 100% of the visitors to your site are relevant to their products (but admittedly I'm out of my realm of expertise).
It is difficult to say how much time I spend on that side of things since it has been built up over time and have pretty high advertiser loyalty - total guess, but maybe 5-20% depending on the time of year. Most of my time is spent acquiring, editing, and categorizing content as well as adding new features to the site.
I haven't really done much research into the various networks, but I do get sales pitches from time to time. My first question is always wondering which advertisers using the network are relevant to my readers (almost always the answer is none). Plus at this point I have a direct relationship with marketing departments, so there isn't really a need for a middleman.
Edit: for people here interested in tech offices, here's the best link: http://officesnapshots.com/offices/?fwp_industry=technology
It's such an obvious model that it's amazing the ad industry hasn't understood how well it works. Instead they persist in using crappy non-functional trackers and ad blocker blockers and all kinds of other bullshit techniques - because apparently they'd rather game readers than provide something good and useful.
Postscript: a minor bug. I'm using OS X Chrome, and the ad bar keeps twitching when I reach the end and try to scroll down further.
Is that scroll bug on all pages with the ad sidebar? Do you run any script blockers?
There is also http://officesnapshots.com/search/
The fact that a website is about interior design is already enough information for advertisers to show you relevant ads.
I think all this tracking is pointless. They still show me ads about fridges weeks after I've bought one.
They weren't ads for Amazon products I looked at last week, or ads for jobs. Good job, it's a really well done site.