I was a little younger when I started on Lackey, but I have to agree. Her more recent stuff doesn't have the same appeal and her older stuff isn't quite as shiny as it was when I first read it. The few 500 Kingdoms books I've read always struck me as... creampuffs -- tasty and fun, but so insubstantial that there's nothing to write home about later on.

I haven't looked at my flist in, um, over a year, so I'm not sure if you're looking for recs. Still, since this series doesn't get enough love, imo:

Shanna Swendson's 4-book series is what I'd call 'chick-lit/fantasy.' Not normally my cuppa (the chick-lit, not the fantasy), but this series keeps me very much amused. It's indefinitely stalled, (due to poor sales?!?), but these first four volumes are quite delightful. If you're enjoying Wrede's Enchanted Forest quartet, you may like this, as Swendson likes playing with fairy tale tropes. The romance angle of the books is played out in such a way that I was not facepalming at the lead female's every move, so I consider it to be above average in that respect.

You also might like Tanya Huff's Summon the Keeper (and sequels), if you're wanting more lighthearted fantasy. Oh! And DWJ's Dark Lord of Derkholm.