Glad your exhibition work is down the road, TD.
Howard has provided you with links to probably the two best well-known test images (one color, one black and white) in inkjet land. They'll get you a far piece towards seeing if your equipment and workflow are up to snuff. Beyond that...
I find, personally, that different images respond to different media. Sometimes I want a cooler, whiter look from the paper, to emphasize contrast and/or the shadows in a print. Sometimes I want a warmer paper, to bring out tonality and richness; or because the subject matter responds better to a little warmth. Sometimes I want a photo-black baryta/luster paper, because I want the deepest dmax and the richest blacks. And sometimes I want a matte paper because I'm looking for a more subtle rendition from an image; or because I want the tactile luxuriousness that it brings.
What I'm trying to say is that the search for papers is likely to be open ended. I'd recommend finding a paper or two to start with, but be open-minded about adding others as circumstances and images and your mood might suggest. Trying a new paper is one of my favorite things.
More generally, I'd highly recommend a monitor capable of accurate color mapping at the (low) brightness and contrast levels appropriate for paper output. The only two I know of are the Eizo and NEC Spectraview. And a viewing station with dimming capability placed right next to that monitor.
Yeah, I know. I was one of those who figured, for years, that they could get away with just having a nice, calibrated monitor. I wish I had back half of the paper and ink and hours I spent staring at my "nice, calibrated monitor" trying to get the colors and tones I saw there to come out of the printer.
Good luck!