Bret,
I'm not sure I understand exactly what you are asking, but maybe the information below will help you. The infoUSA business data does not provide a numeric square foot area for each business (they only provide a size class--A, B, C, etc.), but I use the following proxy techniques:
1) Use Business Analyst menu-->Favorites-->Find Hot Spots (Grids) . . . to create a grid to cover your study area (which could be the entire continental US). Select the size of the grid (e.g. 2 miles by 2 miles) based on your understanding of the standard trade area size of the business you are trying to analyze. (You can use spatial statistics tools to help you determine this, but as a new user, you'll probably be fine with a "gut instinct" decision.)
2) Use Business Analyst menu-->Favorites-->Append Data (Spatial Overlay) . . . to aggregate the business count and demographic data from the standard BA BDS layers. The result will be a map layer with an attribute table that has data summarized by different business types. You can create a thematic map to highlight the hot spots and you can use the Select by Attributes and Select by Location options to query the data for the characteristics that are of interest. For example, you can find grids that have at least 1,000 daytime employees, 5,000 households and a median household income of $50,000 or higher (or whatever criteria you want).
3) If you don't like the business type breakdowns in the standard BDS layers, you can extract the data that you need from the infoUSA data and then use the Summarize Points option under the Business Analyst menu-->Analysis-->New Analysis-->Market Analysis-->Summarize Points. First, you would use the Business Analyst menu-->Add Business Listings-->Search option to extract the business data for a single category (e.g. NAICS 44) into a new map layer. I prefer to use the "Classic View" option in the Add Business Listings wizard since this will give you the most options to extract just the data that you need. After you have your business points, you can use Summarize Points to calculate the total number of business points, total number of employees, and estimated revenue for each grid. You can also use Summarize Points with the Shopping Center map layer to get a total of GLA in sq ft for the shopping centers in each grid.
Using grids (you can also create hexagons with ArcGIS) allows you to evaluate a large market area and see color-coded hot spots for the businesses that are of interest. Another benefit of using grids is that in addition to calculating the total for your business demand generators (counting the number of hotels if you have a rental car business) or potential residential customers (for retail stores), you can also combine that with an understanding of supply by creating a ranked ratio or score for each grid.
If your question was something like "Can this grid support another restaurant/department store/bank/hospital . . .?", then the analysis would have to involve an analysis of the specific competitors within each grid area. In many cases, when you are looking for suitability for a new site location, you don't want to avoid competition, but you do need to understand the market potential (demand) for the product or service in comparison to the supply provided by the competition. Business Analyst Online has a Retail MarketPlace Profile report that tries to identify surplus/leakage for various categories, but I prefer to do the analysis with grids in BA desktop first. (Esri has not made grid analysis an option for Business Analyst Online . . . yet . . . I've asked for this enhancement, but it may take some time before this is available.)
Regards,
-Susan-
