That is something that I have been considering for my table too but I cant shake the idea that they will make actually sitting at the gaming table torturous, with banged knees and bad back posture being the order of the day.
Will the table sit proud of the kitchen units somehow? Getting decent storage under the gaming area would be fantastic.
I never sit when actually playing a game, nor do any of the people I usually play against so that's not really a consideration. Chairs don't need to be pulled up against the table, you can sit with it turned to the side if you want to sit between turns etc. That said, yes there will be a small overhang around the edge as it just makes interaction with the table easier so you aren't banging knees/feet when getting close. Back posture is less of an issue too as one of the advantages of kitchen units is that they are a) higher than tables normally and b) have adjustable legs so you can set the height to whatever is most comfortable.
I tested the theory at a friends house and put in an 8x4 board area in his garage mounted on some old kitchen units we got hold of when he moved. It works very well.
I like having a PC in the den, it gets used to play the radio/music/watch streamed tv/movies and visit sites like this.
As I'm going to need to dig a trench for power etc anyway, I'm going to run an ethernet connection too so I don't need to rely on the wifi going through multiple external walls.