I would say that DL did everything they could to accomodate you. Based on the delay due to mechanical issues, they did give you a hotel voucher. They provided you with food vouchers, none of which, it sounds, you had to fight for to receive (except for a long wait). I recognize it was an inconvenience to be delayed over night and have to deal with these issues but for most of us that travel a lot, these things happen and we learn to deal with them! The fact that DL offered you anything above and beyond was generous as, per the CoC, they met all their obligations to you as a paying pax!