I always like the edible ones- some of the best were boxes of Godiva chocolates and boxes of chocolate truffles. Also liked bottles of wine that the grooms father made himself with cute labels on them. Lottery tickets at each place setting were cool too!
Ones I don't care for are glasses with bride and grooms names on them-I mean what in the world are you supposed to do with those?? I don't like trees since I would never plant one on my property it would just be a waste. Picture frames-have more than I need already.
I have wineglasses with the bride and groom's name on them from one wedding we went to.
Those are the glasses I take to "travel"...if we're going away, we usually like to have a bottle of wine in the room and it's nicer to drink out of the wineglass than a plastic cup. If we go to a cabaret style event, I take those glasses...the point being, if they get broken, it's not a tragedy.
Truth be told though, those glasses have travelled quite a bit, been jostled around quite a bit and are still going strong, so they must be pretty good quality. Thanks Steve and Trisha!!!!!!
In general though, I prefer and edible gift of some sort...candy, cookies, small bottle of wine or other alcohol, the maple syrup thing a PP posted sounded great too. I also like Christmas ornaments. I seem to recall being at one wedding where the centerpiece was actually a grouping of small potted plants, very cute, and everyone got to take home one of the pots at the end of the night. I would also like the sapling thing because I have a yard and so would have a spot to plant a sapling but I can see how for some guests that could be a problem. CDs are good and I just hope the bridal couple has the same musical taste as I do. So far, the couple of times I have received CDs, they've been nice and I have enjoyed having them.
Candles, picture frames...eh...not so much.
Ouor wedding favor was a small round mirror that I glued lace around, with a ribbon with our names and wedding date and a magnet on the back to make a refirgerator magnet. I figured that at least it would be handy for people to tack something up on their fridge. One of my DH's friends thanked us for the "coke mirror" on our wedding video. It was pretty funny.