superking mattress and base selection

Looking to replace king size bed with memory foam mattress which is five/six years old. I have back problems ie sciatic nerve pain. When sleeping in hotels, which generally have super king size beds the pain is greatly reduced. (MacDonald Hotel and cruise ship beds). Studiying your website and looking to purchase from yourself can I supply the following information and ask for your opinion on what base, mattress should be best. Both my husband and myself are around the eleven stone marks give or take a few pounds. Height five feet six to five feet eight. Current mattress is too soft and too hot and is on a two drawer base which isnt sprung. Silent night is the make but dont have any more details. Thanks in anticipation. Can you also supply dimensions particularly the height as we have bedside cabinets headboards etc which we wish to retain.