In the context of your requirement, it is most likely a large office for the CEO or regional company head with a prime view, a private bathroom and the other amenities Artiste metioned. They are usually three or more times the size of other offices and have premium buildout (i.e. fine oak cabinets, granite countertop, and additional plumbing for luxury items like bars, & private showers).
In most other contexts, the term "Executive Suite" is usually referring to a small "full service" office unit that is usually only a few hundred SF in size within a much larger office space that contains the common amenities such as restrooms, conference rooms, copy area, break room etc. These individual suites are each leased as if they were self contained offices, so that suite is for "xyz tenant" and said tenant has exclusive private access.
Unlike regular office properties, they usually provide data & phone lines and service, a receptionist, a conference area and amenities like fax, copy machine and color printing.
They are also much more expensive. A basic 150 SF office space will go from $13.80/SF annually (in my market), while an executive suite can be six to ten times that much. The individual office space typically has other expenses on top of the rent such as data, utilities, CAM fees & janitorial. Executive Suites also typically do short terms and month-to-month leases where small offices usually require a longer commitment.
A lot of small or one person businesses prefer executive suites as it gives a commercial address, business phone and place to meet professionally for clients without having the overhead of a much smaller space (conference, copy, restrooms etc. add up to much more than 150 SF).
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Earl Peterson
Stark & Associates
Commercial Real Estate
Office, Industrial,
Retail & Investment Properties
Reno, Sparks & Northern Nevada
www.starktcn.com