Smart TVs are pretty nice. A few useful apps if you're in to that sort of thing. Netflix, Hulu etc are all a great addition as well as weather updates on power up. Being a new technology, I wouldn't be set on getting one only on the basis of it being a smarTV. The technology has a TON of potential and, while it's a pretty nice feature on a screen right now, speed and options are still lacking on most models I have tried. I have a smart LG in my bedroom that is very nice, although if I didn't get a smokin deal on it.... It would still be at the store.
My thoughts on LED screens...
The choice is LCD vs LED. LED of course! it's thin because the diodes emit their own light! right? Not so much. There is one difference between an old style LCD and a new thin LED. The LCD is back-lit by using a cold cathode. The LED tv's is an LCD that is back-lit using LEDs. This lets the tv be thinner and lighter, but it's still the same LCD panel making your picture. The difference is only in how it's backlit. LED tvs also tend to be brighter in the store. This is true, but only because of the natural frequencies that LED's emit at, your eyes are more attuned. However, this is only important in a store where your eyes are naturally drawn to the brightest picture and you think "hmm that's the best one!" In your house, you lose this false comparison where warmer/more natural colors actually end up looking better.
If a 3" thick TV vs a 1" thick TV isn't a huge consideration.. I'd personally stick with an LCD TV especially when trying to be price conscious.