We have had day beds with trundles and sofa beds (queen) Both are a pain, but the trundle less so (a twin). They solved space issues at the time. We don't miss any of them!

Not a good idea for people with allergies--dust collectors

I can see them being useful for families that have guest children staying the night often enough to justify the expense. I think drawers makes the best use of the space under the child's bed though.

We used a trundle bed for a few years while my son and daughter had to share a small room and it worked wonderfully. It allowed them to still have space to play in the room during the day and not be so visually massive like bunk beds. Now, she has it for when friends sleep over. I have terrible dust allergies and never had a problem! I will say, however, that finding a mattress to fit without snagging was difficult even though the bed was supposed to fit two standard mattresses!

I have a trundle bed in my home similar to the one in the picture but it's from Ikea. We purchased it because of the design the trundle also has 3 drawers underneath which we use instead of a dresser. This design saves a lot of space and The trundle is really useful for sleepovers and guests during the holidays.

Only as a last resort.

I have two trundle beds for my girl's bedroom. They are a pain to pull in and out, a pain to change the sheets on, and they collect a lot of dust on the mattresses. Plus, if any toys, stuffed animals, etc., fall behind or under the bed they get caught when trying to push the trundle bed back and you can't push it all the way in. So you are constantly crawling around to retrieve items from under the bed. I wish I would've just purchased bunk beds.

Great for guests, for couples the 2 together are a King size bed.

Great for over night guest! Would never do it on a daily basis though.

Great for family coming to stay.

Our kids both have trundle beds - they are handy for sleep overs, but I find that it would have been better money spent to have a bigger bed or bunk bed for the same.

Trundle's are convenient - hide-away's are better - Resource Furniture has great options for something other than a trundle but useful when not in use.