IKEA Galant super desk that we had with extensions wouldn't fit at all in the new home office. The Galant is a nice desk, when you have room for it, but in our experience they are magnets for clutter, at least in our case. Even if they have enough space for multiple workstations, they take up a lot of space in any room. This is why we decided to simply sell it and get something more practical. Currently, the IKEA Jonas does the job, we have our sights set on a Herman Miller Airia.
Gary from Germany was in the opposite situation when he was looking for a desk that would fit the entire width of his home office. The IKEA Vika Amon tabletop he chose was a few inches short. Since he didn't want to waste that space, he decided to hack something that would fit. After considering the problem, he came up with a cheap solution: grabbing two extra 2×2 Expedits and combining them with the Vika Amon. Brackets were used to make a nice, wide surface. The Expedits aren't deep enough to fit the entire tabletop, so there is some space for cable management as well as LED lighting strips. Lastly, he added a third Expedit with two drawers on the right side of the desk. The Expedit on the right side has its separator removed, so that it can house bigger computer peripherals, like printers, scanners, etc. Since the desk is set up against a wall, some LED strips would work very well. Even though you might not thing to have a cable management solution, it would probably make things neater. We like how the Expedit with drawers adds some desk real estate, without making the desk too large. In order to keep the airy quality of this home office, extra shelving could be added by using a few floating shelves. That would stop the enclosed feel you get from a bookcase. IKEA Jonas Workstations The Google Desk and Other Tech Desks How to Clean Your Desk in 5 Minutes Living Room Home Offices Loft Bed Workstations (via Ikeahackers, images: Flickr member Mkosut licensed for use under Creative Commons and Gary)