Dear Chris,
The choice of desk wood depends on the look you want and your budget. All woods can work in one form or another. All will be sealed in the finishing. The most popular desk wood is oak and then mahogany.
A plywood top with edge covered in matching hardwood works well to 8'-1". Beyond that you either have to have expensive special order plywood or make a joint. If the joint is part of the design it will work all right.
Build-in desks are usually built in. That is, they are supported by the studs in the wall and are custom fit to the exact size of the opening even if the opening is a little out of square, or out of plumb, or the back is not quite straight. These become part of the house.
I have mastered a Web site on low stress computer desk plans since 1995. All our plans, more than 50, are now free (URL below).
The type of desk you describe is called a door and filing cabinet desk. Traditionally it was made with an interior door and two short filing cabinets. This style is cheap and popular with students.
The more complex version is called a Hutch desk. It has cabinet in the bottom, the desk top, and a over head part with shelves.
I have plans for both types is you want to see them.
Thanks,
Tom Riley snipped-for-privacy@charm.net
Woodware Designs
"Look the Future Straight >Hi,
>I'm a beginner but I think I can tackle this project. I've got a loft
>area where I would like to make a very simple built-in desk to hold my
>computer. I would like it to fit into a 2' by 10' opening. My idea
>was to buy some unfinished kitchen cabinets (two or three) to use as
>the base and attach a countertop to them. Since it's a built-in I
>want it to be fairly solid and I suppose it would need to fairly
>non-porous. What kind of wood should I be looking for to make the
>top? I was thinking some kind a plywood (light oak maybe) and some
>solid wood strips to finish it off. The cabinets would need to be the
>same type of wood I suppose.
>
>Any help would be greatly appreciated.
>
>Thanks, Chris