What kind of parts do you typically do? Or perhaps more to the point: what are you typical "difficult" parts?
If you do a lot of deep boring with difficult to clear length to dia ratio, chip clearance and headstock clearance will become a more dominant issue. You may want to alternate between long and short tools to keep your tools clear of the headstock.
I find that I have been getting very good use out of double tool gang holders. If you can afford the space, you can put a lot of tools on a changer with gang holders. Gang tools are excellent for pilot-drill applications because you double up on a station and it saves time for toolchanging.
I had initially hoped to keep half of my tools the same in my machine, but I find that interference is just difficult to work around unless you have a machine that is oversized for your typical job. Instead of setting up for a generic range of tools, we have been trying to keep the tools that are the most time consuming to set up in the changer. We try to leave long boring bars which have to be accurately set up for height (Y direction) in the changer and swap out the short turning stuff and live tools (which have to be changed anyways) instead because setup on one of the long termpermental boring bars (6") protrusion takes longer than moving in and touching off a few short turning tools (which aren't very fussy).