I agree, the concept 2 is the best out there. As far as treadmills go, it really depends on how serious of a runner you are. First off, to get a decent treadmill, you are going to have to spend a minnimmum of about $1200.
If you want a top of line treadmill, get a True. If you still want high quality but want to spend a little less get a Vision or a Pacemaster. I used to sell exercise equipment and worked for the midwests largest fitness dealer.
If you are interested, PM me and I could probably get you a pretty good deal on that stuff.