The ASL has the Reed Design Registry on CD. Ask at the desk for NA53 R44x 2005. This electronic resource allows you to search by project type/subtype, and by type of staff (e.g. architects, landscape architects). You can also specify the number of staff at a firm, if you want to limit to large or small firms. Coverage is international.
To determine which local architects specialize in certain building types, you can check the AIA Las Vegas Directory and Resource Guide, which has an index by areas of practice. This directory is in the ASL reference section NA55 L37 A48c.
Another approach to local architects is to search the Las Vegas Architects and Buildings database http://www.library.unlv.edu/arch/archdb/arch.php by building type. This database contains information on both the architect and the building, as well as lists of published sources available in the library.