Before I retired, I looked very carefully at the various FEHB plans. Since we were planning to travel a great deal, I especially looked at network coverage. While the CIGNA administered plans (Mail handlers, SAMBA, and the like) had lower premiums, their networks (outside of metro areas) were not as good. GEHA seemed to have a lot of geographic holes. The FEP Blue plan basically makes every provider who is a provider for a state/regional plan a preferred provider for FEP Blue. Since we planned to travel, it provided the best coverage including during trips.
In 2012, Betsy's fall resulted in several hundred thousand dollars worth of medical bills. FEP Blue paid all but about $5K.
I'm sticking with FEP Blue. Your mileage may vary. FYI, the companies are no longer sending out brochures unless you request them.
If you travel a fair amount or (more importantly) split your time be sure to look up providers in the places where you will be. As some seasonals have noticed, their insurance company from back home may or may not work here.
Finally, a shameless plug. There is a National Active and Retired Federal Employees chapter here which meets the 2nd Wed of each month at the Golden Corral on 466. National dues are $40 per year. The monthly magazine provides all kinds of info for feds. Friendly bunch of people and excellent guest speakers.
The NARFE NY federation has a number of tools for comparing plans:
NARFE-NY