I too would certainly go self build.
However a non limited in money cockpit would likely have idea elements of my current build. Of course a much more expensive and expansive version of what I already have been working towards for the last two years anyways. Looks and styling would play a big part, nice lighting too as would the audio and display products used.
Regards tactile, well I already have experimented quite a lot and tested a configuration that offers more immersion than any other "self build" cockpit I have yet seen on any forum. Still though improvements and upgrades could be made here with higher end components. Sticking to the same idea basing it on multiple tactile units (20) or so, all controlled independently and adaptable but working in conjunction with multiple subwoofers which further enchance the tactile sensations. The installation from an audio perspective would have to allow user control and not be a fixed solution, so it is possible to change the role of certain subs etc from LFE to typical stereo response to adapt for various games played.
Motion would have to be used for such an ultimate build, but if money was no limit then various types would of been purchased and tested to determine which one was best suited to my own taste from the leading brands available. Hard to determine which as each brand state their own is better or more realistic. I hate the chirping noise though that some actuators make and find other more motion related versions can create for me motion sickness after a few goes.
Display wise it would have to utilise various displays.
Multi screen 3D would be a must probably something like HD3D Eyefinity as dual links days seem numbered. The latest graphics cards would of course be purchased.
Currently the 7970 is the first ever card to support 4K Tv (4096x3112) via its HDMI 1.4Aa output. Also supporting 60Hz 1080p 3D via HDMI (as yet no actually sold 3DTV have this feature, only supporting 1080p 24Hz maximium). Additionally it also has Display Port but again few Tv Manufacturers have adopted this yet.
30" monitors just are not big enough but, hey money is no object so the ultimate home build for me would have to also have super high res option as well as a big screen eyefinity one. Finally having a dedicated 1080p high end single projector for single screen console games something like the new Panasonic 3D model, 150" - 200" sure what the heck. Furthermore a secondary high end home cinema speaker installation in a fully calibrated room and soundproofing.
For me the ultimate rig would have to offer the highest possible experience for both Pc and consoles yet not be tied down to just one display configuration. The whole cockpit could be on a motorised platform to rotate and screens would be on motorised install to come from either an enclosed unit or floor/ceiling. My own "money no object" rig would have to be imagitive, clever in design and truly look like something from Iron Man's basement.
"I like the idea where imagination would be the only real limitation"