There are a couple ways to set the look of just a single page/post, a whole category, or even the home page.
It all depends on the theme and how they've built it.
What theme are you starting with?
You might be able to use the index.php and remove the sidebar references to create a theme file for just that page.
Or you could create a page template to reuse throughout the site or even across sites.
Or you could see whether a plugin like the Magic Template in the Gold area might do well enough.
And when you decide your time is too valuable to spend diving into the internals of WP themes, let me know.
I've been hired to do some theme/template work for folks here at RRW before.
Good luck!