Best mattress for 12st wife and 19st husband in King size

Can you please tell me the options available to us (most suitable entry level matress and best option if no budget restraints) and why they are the best options? We sleep on a medium 1400 pocket spring by Staples that we have had for 7 years but are both suffering aches and pains in the mornings. We would like a luxurious feeling bed that gives us the support but has a softer sinking feel top layer. We always get a better night sleep when we stay at a hotel so figure it must be the mattress causing our problems. Ideally we would lie a one piece mattress instead of a zip and link as we worry that we would feel the ridge where they join as we often invade each others side of the bed.