You describe a very computer-centric approach to movie watching. The apple TV is living room friendly, TV-centric, normal viewing device. No special attention to what TV would be good to use with an "Apple TV", anymore than you might with a DVD player or any other entertainment component.
I agree about making sure you have room to include speakers or improved sound, if you can. Even the good flat screen TVs don't have much in the way of built-in sound quality, it's minimal, at best. But they do usually have plenty of ports to externalize sound a number of ways. HDMI, component, optical, are common ports in new TVs.
(I have sort of an audio-centric approach to watching movies, emphasizing the sound system. I'd rather have great sound, and would sacrifice screen size in order to preserve the priority of audio, but that's just my personal fixation)
If you already have a stereo receiver, you can use the AUX to include the TV, so you can enjoy the soundtrack in stereo.
I recommend Samsung LCDs in the size range you mention, good deals can be had. Especially if you look for the ones with fewer bells & whistles. Our home as a few Samsungs, two 50 inch ones, and one 32 inch one. The 50" was around $575, and the 32" was around $250-300, somewhere in that range, about three years ago. Probably even cheaper now, and increasingly good image, refined looking.
Good deals can be had on Panasonic
plasma TVs these days. I'm wary of plasma (having owned one from around 2006) because they're power hungry and more prone to repair issues than modern LCDs .
LED LCDs are currently popular, but can cost a little more. According to some fine print I've read, demystifying LEDs, an LED TV is just a variation of LCD, but has more hype associated with it.
In the post-holiday sales, I imagine some really good deals can be found on breathtakingly good flat screen TVs, for a budget shopper. Samsung LCDs are pretty good, I think.