K.M.
There is an incredible destination spa in the Dells called "Sundara Spa". It is ranked one of the top 5 spas in the country. (It is SO not the Dells) I discovered it a few years back when trying to find a great place to go for my sister's birthday. Since then I have had my bachelorette party there, other birthdays gatherings, my husband and I went there for a "mini-moon" right after our wedding, and we have returned there for our subsequent anniversaries.
It is an amazing place. You will feel transported out of the midwest in a very "fung shui" sort of way. It is intensely romantic and relaxing. Though beautiful in the summer, it is also heavenly in the winter as the snow caps the towering pines that seclude it.
It is a spa---which means it is not a "cheap" get away. I will tell you though, it is worth EVERY penny. Really. Pay to stay at the spa in one of their gorgeous suites and treat yourself to a great facial/massage. There are many things to do while there - if you want to - hot tub, purifying bath ritual, yoga, relaxation, hiking, etc. The feather beds are divine. They offer a great breakfast and it is usually about a 3 1/2 hour drive from the NW suburbs. I was there in May and we are already planning another stay before the winter. We love, love, love it there. And, my husband adores it just as much! You also can sometimes get some great package deals in the winter.
The website is sundaraspa.com Check it out. You will be soooooo happy that you did.
K.