Advice between 3 TV's for a Noob

It seems you are chosing passive 3D. Are you doing that on purpose? If not it's worth looking at Active 3D to make sure that's not the direction you want to go.

As for the choices you listed I think the LGs provide more value than the Panasonic and I would only go for the higher end LG if you want the smart TV features.

Bear in mind LG's hz ratings are pretty much straight out lies and their 120hz is really 60hz panel and the 240hz is really a 120hz panel. Also trumotion is only available on the higher end models if you care about that function.

There is also an issue where LG has attempted to mitigate some of the resolution drop of passive issue by rapidly vibrating the 2 540 line fields of a 1080p video on the same line.

I think it's questionalbe what value that has to image quality but do bear in mind that that can only hapen on a 120hz panel and is only on the higher end models (not even sure how to validate which models it happens on).

For me I have an LM4700 which is basically the same set with a sound bar as a combo and I am fine with it becuase it was cheap for it's size and features, I use my PS3 for netflix and laptop for any other smart features and it's a decent performer.

So if size is your main concern and you are fine with the image quality of the 47 you currently have I would go with the cheap 55.

That said remember that at 55 inches the resolution issues of passive become more pronounced so if you sit less than 10 feet from the screen check that won't be an issue for you.

I have the same TV as your #2 option. I absolutely love it. I have no complaints whatsoever with it. 3D quality is great as is 2D. I'm not sure how your other LG set is but the LM7600 has a somewhat glossy screen. Not as bad as a plasma but definitely something to consider if you are using it in a really bright room. One other deciding factor for us was the physical look of this TV. It is absolutely gorgeous. It has basically no bezel and makes the screen look even bigger than it actually is, at least to me it does. Since you don't need the smart tv features I'm not sure if it's worth the extra money but it's definitely a quality TV.

Panasonic 3D plasma displays generally get very good reviews. The passive sets don't fare so well. Spend a lot of time with all these sets and note how they compare. Any weaknesses you see in the showroom will only become more annoying when you get a set home. I have the 47" version of the LG LM7600 and I really like it. I also have a 64" Samsung 3D plasma display. Plasma will give you a better 2D image than the LG, but I prefer the LG for most 3D movies (although not all) because it's so much brighter, and the passive glasses are so much more comfortable and easy on the eyes than active glasses. Most people don't notice that half the screen is dark scan lines in most passive displays, and if you sit far enough away it won't likely bother you, either. I haven't seen that Panasonic, but I've directly compared LG and Vizio in stores, and the LGs look a lot better to me. You could do a lot worse. I'd watch the same material on both sets and see which I preferred. The extra "Smart TV" features don't amount to a hill of beans to me on my LM7600.