Kim,
We were fortunate enough to have Timothy Broschat come and speak at our palm society meeting about Nutrient Deficiencies of Landscape and Field-grown Palms in Florida. During his research he found that weed and feed fertilizers can have undesirable effect on palms and he recommends not using weed and feed fertilizers. Broschat recommends only using palm fertilizer on grass and ornamentals basically everything in a South Florida yard, I have been practicing this in my yard for a few years with great success and my grass is the greenest on the block!! In fact I was skeptical about the ill effect of weed and feed fertilizers, but given his credentials and research I took him at his word. That was until I seen it for myself in one of my neighbors yard.
Jeff,
So, what I do is this: I fertilize my grass/palms with a good palm specific fertilizer with all the micro nutrients with a broadcast spreader around 4 times a year. I then have a lawn service spray for weeds once a year maybe twice a year if necessary. The results for this regiment a very hard to beat!!