I normally pick the iPod hi-rez preset, change the bitrate to 2000, go into the video tab and push the resolution up to its max (I should really create my own preset but I don't do enough ripping to make this a hassle).
This is high enough quality in a single file to look good on a TV or my iMac (I don't have a HD TV so can't say how it would look there, but the 1440x900 iMac screen looks fine), and will still work on my iPhone (the bitrate has to be < 2500 to work on iPods).
I found that the Apple TV preset produced files that wouldn't play on my iPhone - that may be different now though, I haven't tried recently.