Installed 6.1 tonight and I am not seeing Domestic first class options either. I tried to do this fix: 'First-Class Mail Parcel' to 'First-Class Package Service'
but then receive the error message that the Service does not exist and then I lose Express mail and Prioity mail.
Has anyone figured out why first class mail options are not working for domestic? I really want to have the first class mail option for some of my customers.