I love 'em too. I have discovered a lot about them as well. Like, the differences in them. The fuzzier and more like a painting the puzzle is, the harder it is to put together. The easier ones have sharper, clearer lines or are cartoons, maps or city scapes.
I bought two puzzles a while back that I thought looked nice but after I got the pieces out and saw that most were exactly alike, I gave them to someone else and they couldn't put either of them together, so they will probably end up in a garage sale. They're 1000 pieces each and barely fit on the kitchen table!
I bought a puzzle called Home From The Fair and it was a painting by someone named Jack Terry, from Wal Mart where there wasn't a lot of selection unless I wanted a 1000 piece puzzle (too large). I liked it because it had 750 pieces but it took a couple of days to finish because it had a lot of grey/blue/light pink overcast sky and a large, dark green, grassy area along the bottom edge with numerous tiny, blue flowers of various shades and hues. It was also really fuzzy which made it tougher figuring out what piece went where. The pieces weren't distinctive, either.
550 piece City Scape, Cartoon Capers or Made In America takes less than a day to assemble and fit on puzzle trays (a convenient way to assemble and store a puzzle instead of taking up a table) which means I go through them quickly and can't afford to buy them as fast as a I finish them because they are ten bucks each, roughly.
The 750 piece puzzle is my favorite but it barely fits on the puzzle tray.
I bought some of my puzzles at Wal Mart (has the worst selection of all) and three of them at Toys R Us but the Internet has a much better selection if you go through them quickly.