If you ever want to change it backsay when its Christmas seasonjust select all the tracks and change that setting to No.

Alternatively, you could create a smart playlist with music whose genre isnt Holiday and use that as the basis of your shuffle.

When iTunes gets tag information for a CD, sometimes that information has mistakenly set the infamous Compilation tag to Yes. You can change that. Select all the tracks you want to change, then press Command-I and click the Options tab of the info window. Next to Part Of A Compilation, select No from the pop-up menu and choose No, then click OK.