On our second Sleep Number queen-size. Bought the "Monthly Special" some 12 years or so ago. Liked it so much we upgraded and put the first one in the guest room. (And now can't get rid of guests who sleep there!) Then upgraded the second one with an adjustable frame two years ago. Fabulous. Not the split adjustable they show in the ads, which requires a special split bottom sheet. We prefer bamboo sheets, so we stuck with the one-piece adjustable frame.
We follow the instructions that say to inflate the mattresses to 100% once a month, to keep the topper from bunching up. It does seem to help. We both have the same ideal number, coincidentally, but when we aren't sleeping well, it's such a big help to be able to bump up or drop down the firmness a wee bit - makes it like a whole different bed. And the "ZeroG" setting on the adjustable frame is like magic. Set it that way for a few minutes before turning out the lights is like a sleeping pill. Go back to our Favorites position (head up two inches) and it's zonk time.
The VRBO we use when we visit daughter #2 has a memory foam mattress. It's pretty nice, but we always look forward to getting home to our Sleep Number.
