I hope this helps. There is a shopping centre called Belz which is worth a visit, off the south strip past the Mandalay Bay. Don't get a bus it takes ages.
However, the newest one (can't remember the name) is close to Downtown, you can get a bus or a taxi (around $5-10) from Fremont Street. It is a out of down designer type of place, but there are loads of shops and it is worth visiting. If you look on
www.lasvegas.com or
www.vegas.com. the shopping info is posted there.
I got some great bargains in january this year.
enjoy vegas