Certainly not for kids only! My partner and I love the FE and we have no kids. Up until the recent change in the alcohol policy, lots of folks would give the little bottles of booze in the FEs. Here are some of the gifts that I got on my last cruise.
This one had a beautiful frame that had colorful seashells glued to it. Also included was some Disney tissues, Frozen Fruit treats, a flashlight and citrus hand wipes.
This was a water misting fan and a frame that we could have taken to Guest services to have signed by the characters. They don't do the signing anymore.
These were chocolate chips with a note to add to coffee to make a mocha. I think we just ate them.
This was a CD with Disney themed music
And this was just a mix of gum, candy and cleansing products.
That was all in the FE on the first day of the cruise before lunch. This next one was one of my favorites, the Tic-Tac-Toe board was made of material and the Mickey Heads had Velcro on them. It was a pocket, so you could store the heads inside. It took me a while to figure out what it was. The coasters were homemade and a neat idea, but the drinks sometimes stick to them.
Other gifts have been magnets for the stateroom door, key chains, candy, costume jewelery and the like. I have given Disney coloring books with princess or cars crayons. It's completely up to the person also if you give one gift per stateroom or individual gifts for each family member. I have done both. Hope this helps!