If it is at all possible for you, the Inner IDEA conference would be the best possible place. Another excellent place is the IDEA Journal which always provides CeC opportunities.
However, I would check with my certification provider and see first what they are requiring. I assume that you are looking for CECs for the purpose of your re-certification. Not all sessions may qualify for your particular certification.
If you are interested in CEC’s to maintain your Pilates certification definitely check with the School or Organization you Certified through – most do not accept course work from another Certifying Organization. IDEA and PMA both have great options, there is also Balanced Body Univeristy (BBU) who has regional school and traveling conferences.
IDEA has more CEC options for you if you are STOTT PILATES certified, the PMA and BBU are more connected with Physical Mind, The Boulder School, Polestar and BBU CECs. You don’t have to be a member of PMA, IDEA or BBU to attend courses, but membership gives you a cost break. Each Certifying Organization usually has regional studios registered or licensed as their training centers. Those studios often offer CEC courses for the schools/organizations they are licensed through. You should be able to find those online.
If you are local to Seattle I would highly recommend Body Center Studios, they have a great range of CEC courses that are approved for STOTT PILATES CECs.