Dear Phani, I personally own Panasonic 42X20 Plasma and the set is placed just opposite to a huge window. All I can say glaring is not an issue at all. Though reflection is there but you have to manage a little bit of curtains and all and your problem is solved.
Regarding your other question whether it will look dull - Trust me It has enough brightness to fill your both eyes and so your family's. I never ever found the plasma is dull. So dont be in misconception.
My setting is - Contrast 50, Brightness 0.
As discussed lot of time in other threads by other members 720p and 1080p does not make a difference unless you watch your tv from a 2 ft distance.
Believe me even full HD contents looks great in 720p plasmas.