Don't know what sort of aircraft it is but I would say make sure you provide a decent glare shield over the panel, noting Hasherucf's comment about sizing it properly. I find a number of experimental class displays are just about useless for me because of washout and viewing angle effects (I'm not that tall, but tall enough to compromise optimum viewing angles with some randomly placed displays).
I would also provide a well-placed and solid iPAD mount, articulated enough to minimize the specular reflection for yourself and a range of other pilots. Quite a challenge in a bubble canopy, I found.
And having an aircraft with a fairly easily accessible panel reminds me what a joy that is. If you can't manage a one or two piece swing down option, at least a removable top and/or good side access will save you many building words (and skinned knuckles) in the future.
USB chargers (already suggested) and spare breakers are other obvious inclusions, as well as an appropriately placed power outlet for your ANC headphone buggery box. Mine sits in the centre compartment between the seats.
Don't forget to separate out the clean and dirty d.c. supplies and returns, or you'll curse the spurious whines and whirs for evermore
