Thanks again for all the great responses here. I'm happy to report that just tonight I finally made my decision and ordered a king! I went with the Novaform memory foam from Costco (they're on sale this week). I'm a bit nervous -- a bed seems like such a crucial purchase and it's so easy to get wrong -- but I feel like anything will be better than our tired old mattress. I need to decide what sort of actual bed to get with it. Since we previously had a queen I can't use the same box springs with the new mattress. I realize no box spring is necessary, but we don't even have a bed frame of any kind. We may buy a really nice bed sometime in the future, but for now I just want to sleep comfortably! I suppose it will be okay on the floor for a while, but I'll need to think of something pretty quickly. I don't think my poor old knees could take getting out a bed on the floor for too long! Thanks again for your input -- it really helped our decision-making process.

I have an antique iron bed that I purchased from cathouse beds-- the rails were lengthened to accommodate a queen mattress and there's a 2 x 4 support that sits in the L of the rails. The mattress sits on top. I had a normal size box spring with a pillow top mattress on top and it was high-- but plenty sturdy. I had 2 very large dogs getting up on it with me.. and other times 2 adults. My style and needs have changed so I'll be looking to sell the bed-- but it worked out fine for me. Sorry, no pictures of the welds but I bet they have them on the cathouse bed site. I know they have an explanation of the process. I did not much mind the overhang of the mattress when the bed was made-- though it might bother someone who likes a more tailored bed. I could not use a skirt on the bed because of how the railings came in under the lip of the mattress. (edited to remove the photo-- i meant to load one showing the frame/mattress/bedding) This post was edited by funkyart on Fri, Mar 7, 14 at 11:51

Update: The frame arrived in 2 days. It looks very easy to install. Yeah! Boo. It is ONLY designed if if you have a headboard and footboard, not headboard only. It doesn't really say this on the website, just says "use your fullsize headboard and footboard" not that both are *required*. So, I will have to return it. They said the return shipping can be expensive, but they are only maybe a little more than an hour drive, so I will drive it back some time next week. Maybe I can find a new queen headboard while I'm there.

It sounds like you are trying to make this into some type of sofa bed - sofa when not in use, bed when you have guests or need to use it as a bed. I would think that you would need to add hinges to allow for the back side of the sofa to be lifted into place and then you will need some type of pin mechanism to so that once it is lifted you can lock it into the upright position. Attaching the pins to the lower bed will require some sort of wood block that attaches to the back legs and allows tubing for the pin to be secured. I am thinking that you will need to split the foam for the bed that will be the back cushion so it can fold and fit over the bottom bed. Getting this right is going to be a lot of work and require some engineering to make sure everything is stable. By the time you buy good solid foam and material to cover it you are going to be in for a small chunk of change. I am not sure that I wouldn't lose the $90.00 and go buy a futon, sofa sleeper or murphy bed rather than trying to MacGyver this to a working solution.