We will arrive Paris (CDG) on Wed 28/6 and stay there until Mon 3/7. We plan to buy Navigo Weekly for Wed-Mon. But question is what you recommend the best for Monday? We stay in Montmarte, will visit inside Paris and then to CDG in the afteronoon. Thank you & Best regards.
Navigo Day pass 1-5 zone for Monday I think is the best option. The cost is 20.10€ (as of 2023). That cost is similar to 3 single-use tickets in central Paris + single RER B ticket to CDG (2.50€ x 3 + 11.45€ = 18.95€). So if your Monday will be something like 2-3 Metro or bus rides then RER B up to CDG, Navigo Day pass I think is the clear choice for its convenience.
Note that you can purchase the Navigo Day Pass 1-5 zone for Monday at the same time you buy the Navigo week pass. Up to two Day Passes can be loaded onto Navigo cards for up to 6 days in advance.