I see a monitor as a must, and the TV hookup as a luxury / sometime use thing. I have a 27" iMac, so it's pretty rare I connect it to a TV / mirror it.
MY 17" MBP is the Mac that tends to get used with my Sony 46" 3D TV the most...I sometimes mirror my MBA to an older flat panel TV in the bedroom too. The image quality does depend a lot on the quality of the TV...The new Sony is LED and the image is sharp and clear...The best way to check is to compare a few in-store. the 27" ACD takes an awful lot of beating though, Other panels from Dell and LG also seem popular with many users here too.