abbygirl, I think you've married a clone of my DH.

He, too, bought a memory foam mattress a while back, but once I arrived in the UK, it got more and more uncomfortable for both of us. Before scrapping the mattress altogether, we bought a sprung divan base and got rid of the slatted frame.
All I can say is: WOW, what a difference! Our bed now feels like those found in hoitsy-toitsy hotels. My parents came to visit not long after we assembled the new setup and they still rave about how comfortable it is, so I guess it was a good choice.
Do you have a slatted base? I find it odd that mattress & box spring sets are not the norm here.