If you are just looking for a table with city names and coordinates, I would recommend the US geographic Names file.
You can download the data (Domestic and Antarctic Names - State and Topical Gazetteer Download Files) here: http://geonames.usgs.gov/domestic/download_data.htm
There are also worldwide names on the website.
The tables contain many types of features, not just cities, but it should be trivial to filter by feature type. The field names should be self evident, but there is also documentation at http://geonames.usgs.gov/domestic/states_fileformat.htm
The Splat! Documentation mentions that the city file only needs to contains a city name, and lat and long, formatted as a simple comma-separated text file. This would be easy to do using the files I linked above, simply by removing anything but cities, and then removing unwanted columns.
From the doc:
The names and locations of cities, tower sites, or other points of interest may be imported and plotted on
topographic maps generated by SPLAT!. SPLAT! imports the names of cities and locations from ASCII
files containing the location of interest’s name, latitude, and longitude. Each field is separated by a comma.
Each record is separated by a single line feed character. As was the case with the .qth files, latitude and
longitude information may be entered in either decimal or degree, minute, second (DMS) format.
And they give an example:
Teaneck, 40.891973, 74.014506
Tenafly, 40.919212, 73.955892
Teterboro, 40.859511, 74.058908
Tinton Falls, 40.279966, 74.093924
Toms River, 39.977777, 74.183580
Totowa, 40.906160, 74.223310
Trenton, 40.219922, 74.754665