Depends on what kind of atmosphere you want. Also not sure what your budget is....
"Bliss" spa is in the W Hotel - right on Lake Shore Drive / Ontario. The skybar (I think that's the name) is the bar owned by Cindy Crawford's husband (current, ex? not sure). It's swanky swanky and super duper nice. I've had martini's at the skybar on several special occasions.
There is also Spa Space on Canal - it's more in the Loop. Nine Steakhouse is right around the corner and their Bearnaise sauce is famous and it is really fantastic. I'm not sure about a hotel in that area - probably the JW Marriott on Adams and then cab to Spa Space?
If you want a more intimate neighborhood-y experience, you can go to the Wicker Park area and go to Ruby Room - they are a bed and breakfast, spa and holistic salon. It's a really neat space - I've not been (but I live in that area) but my sister had a mani pedi there. Plus, that area is hoppin, so you can have a great time for the rest of the weekend as well. Wicker Park is basically at Division / Ashland (a few blocks north about 3 miles west of Water Tower place).
In the Lincoln Park area you can go the Michael Anthony Salon on North Ave (a few blocks from the North & Clyborn redline stop. There's good shopping there, and a brand new (well, ok not so brand new anymore.... it's like a year old) Flagship Whole Foods (where you can get glasses of wine to carry with you as you shop!!!!!). Michael Anthony is where I go normally to get my mani pedis (I also get my haircut there) and I've had a couple massages there as well. No hotel right there, but get any hotel downtown on the redline and you can just "el" it to the North & Clyborn stop.
Hope that helps! Have fun.