You should take a look at the CO forum on FT, you will get lots of info on your new CO Gold status -- such as the fact that you are not eligible for complimentary elite upgrades on flights to Europe or Hawaii on CO.

Also, if you plan on using CO for your flights to Europe, there's no advantage to actually purchasing your tickets (as opposed to using miles) since you would have to purchase and fly more than 75K elite qualifying miles in order to get a higher elite status than you get with your Centurion card.

Hope this info helps.