Shanghai best visiting time details required!!

Hello there can anyone pls guide. me & my hubby want to plan a trip to SH for fun & adventure. we want to see the night life, new year celebrations, & Snow shows etc with all reasonable shopping malls & other fun liofe a couple can hav. i want to knw abt the season when flights r least charged?? is it December ending??& also if i want to hav fun without much rush at cruise, riversides & malls, is it also December as we r planning to leave last week of Dec 2013 till first week of jAnuary. i heard January is very busy ?? also i need some hotel guidance thats near main buying & visiting places & their rates etc .. pL Z PLZ help