Plus, there is a $50,000 prize purse for the age-group Grand Prix.
The two men put on a show at the 2013 Millrose Games, with Sowinski breaking the American record.
The race is slated for Feb. 2.
Aaron Braun, who will make his marathons debut, leads the American men's lineup.
Inaugural grand prix tour includes six stops; total Tour prize purse exceeds $90,000.
The reigning London and New York City Marathon champion headlines a power-packed lineup.
There are eight men with sub-2:06 credentials, 12 women with sub-2:24 marks.
See the top 25 men's and women's results from the 13.1-mile race in Houston.
Canadian Rob Watson and Brit Jess Peterson won the half marathon titles.
The 38-year old from San Diego captured his 22nd national title.