An employer can pick and choose who they want to offer bonuses or incentive packages to.  They are not required to give everyone the exact same thing-- even if they perform the same job function.  However, when an employer engages in disparate treatment, they do run the risk of being accused of discrimination.  An employee would have a potential discrimination suit if they could show they were treated differently than other employees in the same capacity and that the reason for the different treatment was because they were a member of a protected class.  Protected classes usually include minorities, women, persons with disabilities, and seniors.  If the group that is being excluded from the incentive trip happens to be a group that is made up predominantly of a protected class, then the group could file a complaint with the EEOC or the Texas Human Rights Commission and allege discrimination or hostile work environment based on the conduct of the employer.