Michigane Ave..NICE!!!(One of the nicest and safest parts of Chicago) What hotel.......Michigan Ave is full of great shopping.....From the River up to 1000N. The street is riddled with shops of all kinds from elegant to casual (neiman marcus...prada..etc. to old navy and gap).
Water Tower Place is on Michigan Ave as well (It is an 8 floor shopping mall).
I also recommend State St. (between Adams and Randolph St.) The humongous Marshall Field's is here. It is just a few blocks west of Michigan Ave.
A Cab from Michigan Ave. without traffic (~$7-10), with Traffic (~$8-13).
As for GA's, it depends what you want. I don't think the UC lineup policy has been announced yet. The ellipse drawing is random so anytime is fine, however, if you don't get ellipse and want to be close to catwalk, you'll want to get there at a early time.