Pros
SEIU has a great work life balance, at least in the research department. I want to emphasize that experiences vary greatly depending on departments, but research is nice. I have a supportive manager. We work hybrid with 2 days in the office. Also, many positions (except managerial positions) are covered by the staff union and we enjoy generous benefits, a pension after 5 years, excellent healthcare, dental, and vision insurance that covers pretty much everything, and staff union leadership that fights very hard to defend its members against unfair treatment. We have guaranteed step increases every year as well.
Coworkers are all very friendly, helpful, and an amiable bunch.
Generally it's racially diverse.
Cons
The pay could be better for DC's cost of living, but still very good compared to jobs in nonprofit sectors.
While SEIU is diverse, I know Black coworkers have expressed dissatisfaction with lack of retention efforts for Black workers, though we're in the process of trying to create better racial justice initiatives, so TBD.