I had very good flights on LOT (JFK to Warsaw to Krakow on the way in, Warsaw to JFK on the way home). Two bonuses of flying LOT:
The Warsaw airport is not large and is very easy to make connections in. However, at least in 2013, when changing planes I had to go through security RIGHT after passport control. If I had known this, I would have prepared before landing (I didn't have my liquids bag handy, I had put back on my belt, etc).
You can get Premium Economy on LOT for only about $250 more, each way, than regular economy. The PE seats are much nicer - not just more legroom, but also wider and with more recline. I didn't do it (long story), but will definitely consider it for future flights.
And yes, at least in 2013 I had no problems booking these flights on LOT's website.