In Paris, there's the RER (suburban train line) from the airport, but also some public and AF buses.

Off the top of my head, the Marriott Rive Gauche is a several block walk from a station on the RER line (no transfers required and elevators/escalators rather than being forced to use stairs with luggage). Other "good " stops on the same line would be Luxembourg and St Michel in the left bank (plus Pont Royal but it's not that close to hotels or tourist stuff) probably Chatelet/Les Halles on the right bank but that's a huge station to navigate with luggage. I would avoid the Gare du Nord area as it's rather sketchy IMO, so that I don't even like to change to the subway there. The same applies to Gare de l'Est.

IIRC there's a Courtyard at the train station across the river from the 5th/13th (Chinatown area) where one of the public buses stops.

For the right bank, the AF bus goes to Opera, where the stop is almost across the street from the W. The Westin is about six blocks away, through Place
Vendome.

IIRC there's a bus to Etoile also, so look at hotels in that area of the right bank. Unfortunately Prince des Galles isn't close to any convenient public transportation to/from CDG.