I wish you the best. A showroom can either be boom or bust, and they are not cheap as you know.

The last one I was associated with had a high-end theater & medium end one...
Multiple in ceiling in wall speakers with switching.

A nice conference room (stick a Kureg coffee make in there)...

A funtional contol system with an ipad.

Examples of what the various devices look like for Alarm, lighting etc.

Best of Luck!