What do you recommend for imaging of non-adherent cells?

Answer

You can do imaging on suspension cells. If you are using phase-contrast you won’t get much since the light reflects off of the cells in suspension, but you can get images using other types of microscopy. Confocal and fluorescent imaging is possible. Often fixations are necessary. The trick is using an ultra-thin layer of cells and short working distance. If you do a search on the internet for whatever imaging you want to do and use the word “suspension” you will find a protocol.