I can't speak to Houston, but I have attended the Machine Quilters' Expo in Providence, RI for the past two years. Each vendor has at least 2 setups (most have more) and there seems to be ample time for anyone who wants to try the machines. I actually didn't see lines of people waiting or anything like that.
That's where I fell in love with the HQ Sixteen Sit-Down that I vow to get someday!!