My idea of home theatre is whatever is on HBO around 10PM on Saturday...just need something that is basic and nice without the technology hassle.
Let me preface by saying I'm not an "expert" per se but I do research stuff to death because I can't stand making a bad purchase.
I would go Plasma 55-60 inch for a few reasons. Plasma will get you the biggest screen for the lowest money and the highest refresh rate. If it was a well lit room I would go LCD or LED (essentially the same technologies with different lighting mechanisms). Plasma gives more contrast for darker colors (blacks, dark blues, etc) vs LCD and LED giving the brighest bright colors.
I have a 46 inch LCD in my well lit family room and when watching sports at night I couldn't watch it on vivid setting because the colors were actually too bright. Only time I use that setting is for animated movies for the kids (shark tale, shrek, etc), anything with actually actors or live action you'll want the dark contrast. If I tried to watch Sherlock Holmes on the vivid setting half the screen would simply be a black blur at parts although I have the standard settings worked out to do better there. Plasma's can actually power down specific parts of the screen though and acheive absolute black vs LCD or LED still projecting the color as black. LCD and LED are a lot better there then they have been but not as good as Plasma just based on limitations of the technology.
From 12-15 feet off anything bigger than 60 inches would risk pixelation even on a 1080p. 1080 has twice as many pixels as 720p but still, the larger you get the larger the pixels will be. Anything you get that size you will be able to see pixels from 5 feet in.
Downside to Plasma are they are the heaviest, they are the most power thirsty, they run the warmest, and they cannot be laid over on their side in transit. Must keep them upright to avoid potential issues. The plus would be deeper colors, higher refresh rate, and power usage doesn't mean quite as much if you're getting the same size screen for $700-1000 less than an LED equivalent. Plasma is the old dog on the block and I thought would disappear for awhile but they have reworked known technology recently and really brought it back well for a cheaper price because it's been around so long. Think Chevy Small block engine still running in the current Corvette's, yes it's older technology but it's been reworked so many times that it can perform like a champ still.
Hope this helps, and if price tag is no issue feel free to go LED, but given that it's the basement I think Plasma will get the job done as well or better for less money. Don't go into a store to look at screens next to each other. The TV store's are set up to sell whichever unit gives them the highest profit margin. It's not that hard to set up a very good TV to look bad next to a lessor TV on it's best possible settings with a better HDMI feed into it. Narrow it down to a few units based on online feedback and make your choice without some salesmen yapping in your ear. You also don't know if one display TV is fresh out of the box and another has been running displays 18 hours a day for 6 months.
Brand wise, I swear by Samsung personally at this point but I know others that have good luck with Sony, LG, and Vizio. TV's are one thing where you don't want to go with an off brand because there is a noticable quality difference especially when you get into bigger sizes.
