Here is an interior shot from the Panasonic LX1:
You can get wide angle zooms made for digital slr's that have the sensor crop for about $400 to $800. I have the Tokina 12-24 f4 and Sigma 18-50 f2.8 for my 10D.
You can also stitch photos together to make a panaramic photo using your existing point & shoot. If you can find a used Nikon Coolpix 5000 or 8400 they both had 28mm equivalent lens and the 5000 had an accessory lens that was 19mm equivalent. Unfortunately the older P&S cameras have severe shutter lag and other problems compared to the current bunch.
The pelican of digital photography is dpreview.com.