The vast majority of LCD and LED televisions are IPS these days, it's just not a marketable thing. That said, in sizes like 42 inches and larger, why not consider a plasma? Panasonic in particular have gotten plasma to the point where it's as good in terms of power consumption as their LCDs, while being cheaper and still holding the traditional plasma advantages like refresh rate and contrast ratio. The only real downside to modern plasma is that they tend to be a little heavier, which is a consideration if you are mounting it to a wall.
I sell TVs for a living, and I've got to say I probably wouldn't own an LG after seeing the number of them that need to be repaired. I don't know about Vizio, as we don't get that brand where I live, but Samsung plasma seems to have much higher power usage than the Panasonics (spending all the R+D budget on LED backlit LCDs? They certainly are pushing them hard...)
Just a few thoughts, anyway.