Suite perks are far greater on Oasis class.
CK is a restaurant I'd describe as better than the MDR but not quite specialty (although night one filet mignon is excellent).
With a suite on Allure you would also get free WIFI for each person and free beer, wine, soda, bottled water, etc. in the suite lounge from 11-11 each day. None of those perks are included on smaller classes.
Of course, the prices usually reflect the differences. Also, everything I wrote applies to full suites, not junior suites.