I like Land O' Lakes butter, but our local grocery store chain also makes a store brand that I'm happy with. At the chocolate shop I used to work in, we used Pluegra, but I'm too poor to afford to bake with that! 
You can decorate gingerbread, flat chocolate chip cookies, or any kind of cookie that has a reasonably flat top when it's baked.
Deanna
As long as the butter is fresh, most any brand will be fine. Most people can't tell the difference between store brand butter at $2.00 a pound and the best organic European style at $6.00 a pound.
Cut outs can be sugar, chocolate rolled, gingerbread, and shortbread. Just search out rolled cookies for more inspiration.
The manufacture of butter is regulated by the FDA. They require a certain water/protein/fat ratio for a product to be called butter. Therefore, all basic butter should be the same. There are other brands out there which provide for a higher fat content. These appear to be best for baking, especially in pastry.
Plugra is a high-butterfat content butter, expensive, but carried in most larger supermarkets now. There are other European imported brands available, but I do not use them, so I am of no help to you to find them.
Technically, any cookie can be decorated, but rolled cookies fare better with decorating, as they have a smooth surface. I have seen decorated chocolate chip monster cookies and peanut butter cookies sold in malls.
Of course, cookies that are loaded with goodies would not do so well, as they have lots of texture to the surface.
Theresa 
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