Replacing mattresses but don't want to have to turn them

We have two slatted beds, pushed together (Warren Evans) and have had the mattresses about 13 years. We both (in our 70s) suffer from aches when we get up in the morning and I (8 stone female) find turning over in bed quite uncomfortable in my upper back and neck. Can you recommend new mattresses for us, preferably that we don't have to turn, as it becomes more and more difficult with age! I've tried memory foam and don't like it at all.