I have to say I am blown away by the number of kids in full and QUEEN beds! Wow...
Just remember, if/when your kids go off to college, it'll be a TWIN (XL) for them!
Also, with regards to "keeping a bedroom set into adulthood". Yeah, okay. That idea is laughable to me. I slept in a twin bunkbed until I was 15. By that time, the furniture was SO trashed from me and my sister using it, it had to go when we moved. We each got a new room in our new house. We each got a TWIN bed. When i went off to college, after my first year in the dorms, I moved into an apartment, and took my OLDER sister's twin bed furniture set with me (since it was pretty trashed by then too). I slept in that twin bed until I graduated college. AND, I met my DH during my sophomore year. WE BOTH slept in my twin bed on occasion.

We got married a year after graduation, but I spent a year living at home while he was off training, and I was STILL sleeping in my twin bed at home.
I moved to a Queen bed when I was 22, and DH and I bought our first bedroom set together. My mom offered me some of my old bedroom furniture, and I laughed at her. No thanks! Tastes change into adulthood, is all I'm saying...
Why anyone would think a 3 year old child needs a QUEEN sized bed is beyond me. Talk about spoiling...
I'd recommend getting what will FIT in your child's bedroom, without needing to move all their toys to another room to play with.
EVERY single child can very comfortably fit into a twin bed for a LONG LONG time. My 3 and 5 year old boys sleep in a twin over twin bunkbed, and they look TINY in them! And, my three year old is a "big boy", height wise.