How to plan the future panel?

I've been tasked by my flying club http://flyingclub.org/ with a job I've
been trying to do informally anyway: design our "panel of the future", and
draw up a plan for getting from our current state to there.

The mandate is pretty wide, though I get the feeling that an electric AI is
more likely to be approved than a wet bar.

We've four aircraft (all Cessnas: two 172s, a 182Q and an R182 (RG)), and
one of the policies we want to continue is to have equivalent panels in all
aircraft. For example, we've Garmin 430s and Strikefinders in all aircraft
today, so someone hopping into one or another will know how to use these.

Of course, we all know that no plan survives contact with the future (to
misquote). But having a plan means that we can be coherent about changing
the plan.

So...what's a good way to go about this?

Obviously, I can start with my wishlist and add to that the collected
wishlists of all the other members. But how does one prioritize? I'm
thinking that enhancements should be ordered by safety and then increased
utility. But even that begs the question.

For example, how important is a backup electric AI given that we've standby
vacuum systems (off of manifold pressure)? How does a backup AI compare
to, for example, Cockpit WX, in terms of safety? What is the "cost" of
having Cockpit WX on a separate device (ie. more learning) instead of
displaying directly on the 430s?

[FWIW, over 75% of us are IFR rated though I've no idea how many fly how
"hard" IFR.]

How do other clubs, partnerships, or individual owners approach this type of
planning?

Thanks...

Andrew