tkelsb, I had close to 140k miles on mine when I changed the fluid, and my transmission is still shifting perfectly at 207k miles.
I would not do a flush on any transmission that has not had the fluid changed for 100k miles. What I would do on yours is just drop the pan, which will take about 1/3 to 1/2 of the fluid out of the transmission, and just refill it with new fluid after changing the filter. This should give you about a 50/50 mix of new and old fluid, and this is what I would recommend on any car that has been driven more than 100k miles since the last transmission service. I have heard horror stories of transmissions failing shortly after flushing or replacing the tranny fluid, but I've done this many times on many cars and have never had a transmission problem that was caused by changing the fluid.