I believe there may be an issue with the settings for one or more of 727-300/400 and the 737-800/900 (have not flown the other models yet) pilot and crew needs. I am not sure what end it is on but when going from 737-400 to a 737-800 I am having to increase by 10 pilots and 10 crew for a 7 plane rotation. The specs on both of these planes are 2 pilot and 4 crew Y162 standard. My configurations were YP110, CS10 on both models. I am failing to see why I need to increase my personnel for this change. In addition to this I was also adding pilots and crew to the 737-300 to 737-800 change 10 pilots and this time 20 crew. I do know that going from the 300 too 800 is a one crew increase and I expected to go up some but I believe it should only be 10? I am not sure if it was the older 737-300/400 or the 737-800/900 which is wrong but one of them needs to be addressed. This costs a significant amount of capital for the additional personal and either this needs to be felt earlier to weed more airlines out or fix the over need and relieving the additional costs. If their is another reason for the increase could you please explain that to me as well as there is no announcement for example additional crew needed at such a such date and if so that should effect both planes at that date and not when switching so I can not think of a good reason other than something is off.