I have a memory foam mattress topper at our holiday cottage, mention that as I only sleep on it maybe a few weeks out of the year.
I didn't really get on with it until I put an extra mattress protector over it, I've no idea why but this made a huge difference to the quality of my sleep but it did.
I already had the fitted zipped sheet that was supplied with it, then a fleecy mattress cover on it (I use it mainly in the winter months), and now a normal fitted slightly padded mattress protector and its perfect.
Can't remember where we got it (dh ordered it online) but it wasn't cheap £150 12 years ago. The frugal me would rather suffer for a few weeks than dump £150

The topper was bought for our use not for guests, me being fussy I wanted our own "bed". It's a job of work to get it in my lock cupboard lol