Hi GrumpyOldPerson,
Now that you know what components are in the Mattress you’ve enjoyed for so long, it will make it easier to ‘zero in’ on the type and focus on the comfort. Keep the Mattress Specifications You Need To Know and the Mattress Durability Guidelines in mind as you look. As long as the memory foam is of good density and thickness, you can focus on how it feels for you both. Being lighter sleepers,
I would not be too concerned over the coil support layer- any good mattress will have good quality innersprings. Focus on the feel - Remember the moral of the Princess And The Pea - she proved by her sensitivity to something wrong in the mattress that she was a real princess, got the great bed, and her prince!
I trust, with a bit of due diligence, that you can find a great comfortable mattress that will suit you both!
~ Basilio