In DS9 there seems to be around 5 ships around in the Area of DS9 (prewar) being a day or so away from it at most. Also in redemption they seemed to be able to assemble 5 ships at pretty short notice.
I thing that it be quite reasoble to assume that you could see a denisity on the borders of around 5 starships per 10 light years square.
Inside the fedeartion that would most likely drop 1-2 per 20 light years.
And also out side the federation you would find ships out on there own with backup much further away.
This does not include Auxillary ships though.
As far as those 5 ships go Im guessing and this is pure speculation! That you would find 1 battleship like ships a Galaxly/Nebula/Ambassador/Sovereign, 2 Crusiers either a Excelsior/Cheyenne/Niagra/Akira/Steamrunner/Norway. And 2 Frigates like Mirandas/Sabre/Freedom/Constellation/Defiant. This wing would be commanded by a Rear Admiral or/and a comadore/senoir captain.
Though Im sure the composition would change depending in the area and situtaion and that they would be brought together to form larger fleets when needed.