Mort: yeah, I asked and they said that they didn't have them. Maybe she meant in our particular building. I remembered them saying to me when I booked that I should have a room on the main floor as there were no elevators (which is strange cause at All star Sports they have them!). They weren't willing to work with us at all it seemed, we found the CM's there to be very apathetic. But it all turned out okay, we ended up switching resorts in the morning and had a great stay the rest of the trip divided between the WL and the CR.
Now about the trundle...it is NOT anywhere near the size of a twin bed, and the consistency is that of a 'gym mat on a shelf with sheets" as my husband puts it.
It was only about 3 inches off the floor (i didn't like that fact, but since dd didn't complain I let her sleep on it) only in the morning did she tell me that she was up all night and how relieved she was we were moving resorts.
Every time we book now she says "mom will i have to sleep on the shelf?" LOL
I have heard of adults sleeping on these but I don't know how they would do it. She was four feet at the time (she's about 4'5" now) and she was just miserable.
But since this is a gift (and what a generous gift too, I might add! What a great person you are!

I'm sure the family will be thrilled with whatever you pick for them.
I would seriously though, esp. depending on the ages of the kids, consider doing 2 rooms at Pop or an All Star. Boy, do i miss the days when WDW had real roll-away cots instead of these 'trundles' that aren't even really a bed!
hope that helps! I don't mean to offend anybody who loves the resort, that's the beauty of WDW there are themes that are for every taste.
some people like the secluded feeling of the resort but i like to be close to the action...the bus...it took us forever to get to the CR when we wanted to see about switching resorts and the CM's at the desk weren't very helpful at POR. We took a long bus ride and a boat to the CR and I was like "Pleaaaaase you have to find us a room" LOL they were very helpful and we were saved

if i had it to do over i would definitely have taken a cab LOL.
edited to add: Oh! I forgot! The one thing we DID love about our night at POR RS: Boatwrights!!!
by the time we got back from getting our ressies squared away at the CR, we had been rained on twice, we were exhausted and we were starving. We stumbled into boatwrights and had one of the best meals of our trip. DH and I split the pot-roast cause it was late and we didn't want to eat huge...it was phenomenal!!! would like to eat there again, and we may be cause part of my family is staying at POR RS on our upcoming trip.
I admit it, i tried to talk them into WL...no avail LOL
geek