Generally speaking your higher frequencies experience more loss quicker as your coax gets longer. Try
this calculator and see the difference with various types of coax. Don't change "SWR" or "Power In" on the left, just try different lengths, types and frequencies and notice the change of the top number on the right. That should tell you what you need to know. The higher the number on the right the worse the choice. Balance that against what the different cable will cost and remember that the larger diameter ones will be harder to work with, which also may or may not be a factor.
Take for example my two set-ups. In my car there is about 8 feet of RG-58 that I got for free which is quite small and easy to thread from the roof to the scanner (I actually drilled a hole and mounted a well grounded antenna which I think gained me more than anything). At 800mhz that's about 1.2db loss, I can sure live with that. At my base station I have about 60ft. The same cable would give over 8.5db loss at 800mhz, I don't want it even for free. Currently I have RG-6 up there which knocks the loss down to aobut 5.2db. It is still fairly easy to work with and I got it for about 20 cents per foot, a reasonable comprimise. Once the weather gets nice this spring I think I will spend the money reqd and improve upon that though, I have a few things that are a little weak that I would like to bring in better.
EDIT: I should add here that the whole setup can depend on how far away the transmitter is. When I lived in the city I monitored the local 800mhz EDACS system with a BC245 sitting on the desk
with no antenna on it. Sometimes a bit of attenuation can be a good thing if there are a lot of other things high powere nearby on similar freqs. Out in the country aobut 35kms from most of the stuff that I want to listen to I need all the help I can get.
