Cymbidium orchids are semi-terrestrial plants, meaning in their natural habitat they grow in light soil that contains ingredients such as fir bark, peat moss and perlite or pumice. So if you were to plant your cymbidiums in a raised bed, it would have to contain light soil that includes such ingredients. Also, many people enjoy bringing the plants in for display during the winter when they bloom, which is impossible if you have them growing in a raised bed. So, though it is possible to grow them in raised beds, it is important to realize that they have special growing conditions that may not jive with other plants you wish to plant in the raised bed. For that reason, it is often easier and more satisfying to grow them in their own containers with just the right soil mix.
Cymbidiums like to be slightly root bound, so when repotting stay in the same size pot or just one pot size up. Your main reason for repotting will be to replace worn out planting medium--for instance, bark tends to break down over time.
FYI -- For my Cymbidium Orchids, I use coconut chips for repotting. I think it lasts longer than other 'Orchid Mixes', which usually contain Fir Bark. After growing in the coconut chips (often called 'Core')for 3 years, I see very little breakdown in the potting media. It is easy, clean and no mixing of anything. I use it as it comes from the bag or bale. (it comes both ways) My Cymbidium thrive in this stuff!!