We have a memoryfoam mattress on platform bed, for over a year now. You can basically do whatever you want, according to budget and taste. Your foam mattress can rest on a solid plywood sheet, or slats. As far as I know (from reading a lot in a mattress forum), there's not need to put it on a box spring or foundation. Supposedly, slats vs. plywood vs. the floor will change the feel slightly. We have modern platform with slats and a wood frame around the bed (with headboard), no footboard. The least expensive setup would be a standard metal frame, slats or plywood on that, and headboard of your making. I would attach the headboard if it were me. With a metal frame, you'll need a bedspread to cover it, and you may hit your shins as you walk around the bed.

It's been there so long that dh would probably squawk if it were gone. He does turn it on every once in awhile but I unplugged it one time & it was a couple of weeks before he noticed. And this is terrible but I like the bulk of it because it keeps dh from piling more stuff onto his table. Flowers, even fake, are out because of dh's allergies. When we build our next house, I am going to have wall lamps and very small tables next to the bed. So for now, it's all about getting this place ready to sell.

I think the headboard is a great idea and will make the beds feel more like a sofa. However, for sitting comfort, you may still want the bolsters, and some other pillows as well. My first apartment was a studio and I had a twin bed pushed up against the wall. A twin bed is really too deep to sit on comfortably--you have to wiggle way back to get your back next to the wall. And this usually means that people put their feet on the bed, as well. If you think no one will really use these beds as sofas, not a problem. But if the beds are intended to be used as seating often, to make them comfortable, you need a fair amount of cushioning back there. The bolsters shown in that link are a good start, but IMO, not nearly enough to make a bed a comfortable seat.

DK- Last year one of our cats ate my entire ASPCA approved pet-friendly palm plant. He ate little bits at a time so as to not raise suspicion. When all was said and done, we had spent $5,000 in surgery & vet fees to have the contents of my plant removed from Hobbes’ lower intestines. I love love love the look of real plants in any interior space. If I could, I’d fill up my entire house. Unfortunately I can’t risk endangering my babies again. I don’t know what’s wrong with them lol. The other day my husband dragged a leaf in on the back of his work boots. It took less than 4 minutes for me to find Hobbes huddled in the corner having a little snack. Hold on I’ll take a photo of my living room for ya