Our bias is to move a show each year because a new location draws a fresh crop of attendees. (Remember on average, half a show's attendees come from within 100 miles.) Also, your repeat visitors like to visit different cities and it helps your negotiating clout to move around.
On the sales side, a new facility allows you to redraw the floor plan, which, if done correctly, can "encourage" the front-line exhibitors to expand their space. A venue-bound show has to wait till the building expands.
However, there may be valid reasons to keep your show planted in one location. Perhaps only one facility can fit your show or your attendees are concentrated geographically (such as Los Angeles for an entertainment show). Or you simply like the familiarity of the same venue.
Unless there is a compelling reason to plant a show, the recommendation is to move it each year in a regular rotation (such as east, central, west).