Do you have a particular brand you are looking at and budget?
I use mostly Canon so can only advise you as such. Having done graphics for large output, i.e. banners, billboards, murals, fleet graphics and booth designs, I can tell you the higher resolution doesn't hurt. If you plan on going digital, look at the mid to higher end models for the resolution factor. Not for the megapixels, but more for ISO sensitivity and "pixel size". Makes it easier to enlarge with out too much loss of image quality. It does come with a price though, but not too bad. I borrowed a full-frame digital DSLR, the Canon 5D, for a job recently and was sold on it. Will upgrade soon from my current set-up. Was able to print 48"x96" prints with great results. The 20/30D is a great camera, but the 40D is about to be released so if you want to wait, everyone is drooling over that one. It has a 1.6x cropped sensor, but can print enlargements up to 36x48 with ease. Really depends on the level of image quality you need in the larger output. For display purposes, I doubt the printer will use anything higher than 360dpi.
The other aspect you have to look into is the lens and lighting. That is where the difference will be had. You can use the kit lenses that are bundled with the camera, but they are probably too slow for what you need and image quality will not be as good. You will probably want a decent wide-angle lens to capture the space, detail, color and contrast. There are plenty to choose from so just decide on the range and speed you require. For indoor with limited light, the prevailing opinion is to go with a fast prime or zoom. The EF 24-70 f/2.8 L is an excellent example if it's not too pricey for you. There is also the new EF 16-35 f/2.8 L. On a crop sensor, the EF-S 17-55 f/2.8 IS is another option. The larger aperature will really help indoor shots. I have the 24-105 f/4L IS that is bundled with the 5D, and it's just too slow in low-light.
As far as lighting, you will probably need to use a bouncer of some sort so you do not get too much glare off of the surface, yet light it sufficiently. I do not have too much experience using softboxes, strobes, etc. so cannnot really help you there. I have used my flash unit with the off-shoe cord and a simple bouncer to reflect light indirectly. Works for me so far.