I know you asked about treadmills but have you considered an exercise bike instead? I had a treadmill and I found it really annoying because either I was looking at the wall while I ran or my back was to the wall which I hated because I was always paranoid about flying off the back - it's never happened to me but it could yanno. I've seen it on youtube and funniest home videos I know.... I have some odd fears

The bike was cheaper and it fitted nicely into the lounge room where I could ride and watch TV or chat to DH.