Hi efree
Welcome to the forum. If you can ad these services they represent value-added to your clients. You should therefore be able to charge a premium for your service.
Of course, should it be the case that you don't actually know how to rank sites there is a few of us here that will be ready to clean up afterwards.
But seriously, if you are knowledgeable (the mention of submissions makes me wonder) you should definitely offer
SEO as a core part of your service.