Okay, first off, what's the lighting situation in that room?
If you have a lot light, definetly go with an LCD. Even if it means you need to get a smaller TV, you want to have an LCD. You don't want your picture to be ruined with glare, which'll just drive you crazy.
IMO, unless you game a lot, there's no other reason other then lighting to go with LCD. Plasma packs a much crisper, detailed picture, and while it's two different "tastes," I don't think you can go wrong with plasma. If you like a more subdued picture that's a bit more "relaxed," go with LCD. If you like punch in your picture, plasma is what you want.
If you want to go above a 46", I'd say go with plasma for sure. An exception would be the Sharp 52" Aquos 1080p set, which is $4K MSRP, but as to what they go for online, I'm not sure. If you're going to go with a plasma, a 50" set would be nice, and a Pioneer would be pretty kick ass. If the Pioneer's cost too much in your book (their 1080p plasma is $8K, the non-Elite 720p one is around $4K), I really like the way the Samsung 50" plasmas are performing (not their higher end one, I'm liking their lower-end one for price vs. performance). The higher end model will give you a CableCard slot, which sucks at this point b/c of lack of PPV and OnDemand, plus gen1 problems, as well as an additional HDMI and better post processing. That processing will help out the SD picture quality quite a bit, but lets face it, most people watch mostly HD on an HD set. At least I do

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If you're not a Samsung guy, I'd say check out Panasonic next. Their 50", as well as their 58" sets are quite sexy, and def. something that I'd be interested in. I'd say stick with the 60U opposed to the 600U...not worth the price difference IMO. The Hitachi 55" plasma is real nice. They just launched their 06/07 line, and the 55" actually swivels by pressing a button on the remote with a built-in motor. Useless, but cool as hell nonetheless. Quality is def. up there, but because of my personal preference, I really like the Samsung. From what I've noticed, Samsung tends to over-embelish their reds a little bit, but I don't really find that to be bad...I think it gives a nice punch to the picture.
If you're def. set with LCD, then I'd check out the Samsung's. I'm not a big fan of the Sony XBR line, just b/c I find Sony to be a shady, overpriced brand to begin with, so yeah, I'm a bit biased. Samsungs 4095 or 4096 40" LCD's (both are 1080p) are nice, but the 4092, which is 720p, actually looks better, IMO. They also have the 46" as well, but I find that their 46" non-1080p set doesn't look too good compared to their 1080p one. Not sure as to why this is, but that's just what I've noticed. Samsung also makes a killer 52" LCD (which I think is 1080p) but MSRP on that is at least $5K.
If you do like Sony, check out their 46" XBR. MSRP is around $4K, and the design is nice, and the picture is nice as well, but I don't think it's worth the extra premium over either the 1080p or 720p Samsung LCD's. Of course, this is just my opinion. There really is no right or wrong in this aspect.
Either way, if the lighting can handle it, I honestly believe you'll enjoy the plasma more. I do sell TV's at Best Buy, and every time I show the Samsung 42" Plasma next to the 40/46" LCD, almost everyone likes the plasma more. The LCD is much brighter, but there's just more detail in the plasma, hands down. Of course, calibration does a lot, but you're just going to get better color in the plasma, hands down. My favorite plasmas, once again, in order, are Pioneer, Samsung, and then Panasonic and Hitachi tied. Fujitu is great, but I haven't seen their new models, though my neighbor owns their older 63" which is absolutely fantastic.
Something I really want to stress is 1080p, and it's lack of importance. Pretty much all the epxerts are saying you need at LEAST a 50" TV in order to see the difference between 720p and 1080p. A 52" may show a slight increase in quality, but honestly, I doubt you'd notice it, and if you did, you wouldn't care enough. Fact of the matter that as long as the TV deinterlaces correctly, all movies being "shown" in 1080p are equivilant to 1080i anyways, so it doesn't matter. Besides, 720p is plenty. Let's get realistic. Cable/Satellite can't even get more then 20 channels at a time in 720p. Do you really think they can handle 1080p, which takes MUCH more bandwith, anytime soon? Flat out answer? No. My bet is that it's going to be at LEAST 10 years till we see that. Blu-Ray is pumping out 1080p right now, yet with a Samsung 40" 1080p LCD, switching from 1080p and 720p shows NO difference to my eyes from a normal viewing distance. Of course, once again, my opinion.
You may want to save some money on the actual TV and go with a wall mounting solution as well. Wall mounting is probably one of the coolest ways you could set up a TV, and it looks KICK ASS once its all said and done. Most people just get a tilting mount, but full motion mounts are available, which atually let you move the TV all around, swiveling, tilting, pulling it out, etc. It really makes it look amazing.
Phew. If you have any more questions, feel free to post or PM me

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