Lots of bookshelves. All the way to the ceiling, at least on one wall. Places to put up my posters and pictures. No hassles about work-area toys. Couch, preferably a variety of couches.
Offices have plusses and minuses.
Plenty of ethernet. At least 4 ports per office VLANnable to whatever test lans you need them to be on. And as many hubs and switches as you want for in-office things. Room for at least 3 workstations in the office, per person. Sometimes you really need to have an end-user system for end users.