You do not need to serialize values. If the value needs to be serialized, then it will be serialized before it is inserted into the database. Remember, resources can not be serialized or added as an option.
You can create options without values and then update the values later. Existing options will not be updated and checks are performed to ensure that you aren't adding a protected WordPress option. Care should be taken to not name options the same as the ones which are protected.