In the DS9 tech manual, it gives the crew complement as 750, the same as on the Nebula-Class (a much larger ship). I always cap it at around 550, but then after the war Starfleet would be suffering a shortage of manpower so every ship wouldn't necessarily have a full crew.
Commander Austin Harris, First Officer, Deep Space Nine (by FltCpt. Bossco)
8.01 - Darkest Before Dawn
(Chapter 8 added, 12/09/2015)