Run a search on futons.
I had a small fold up 3 piece that you could make into a seat on the floor with a backrest or unfold flat and sleep on it. Futon mats are also something to read on. New ones did not bother me, after using for a bit the memory foam mattress toppers were something I looked at and eventually bought for when sleeping on it.
I have a real bed these days but when a futon chair was offered by someone moving I brought it home. It dismantles into small pieces to be easy to move up apartment stairwells or anywhere else.
The chair has a foot stool and if you fold the chair flat and use the foot stool you have a bed.
Once again, memory foam wins in my opinion.
I am not against cots, but do some research on how to size things so you don't wind up with some of the issues others have mentioned. It is not a big deal to sleep poorly and cramped up for a few nights. It is a huge deal to do every night for a long period of time.
Futons made out of wooden frames that are easily dismantled are my choice for what you are talking about. I have never had experience with a big cot long term, dealt with old style cots in scouts and here and there over the years and overall it would have to be something in excellent shape for me to mess with one these days. Bit enough to easily fit on, and not something that would sag over time like someone mentioned with an aluminum cot.
I consider a futon simpler.