The 2 hotels are different in style. Marriott RG being modern, big and more business oriented while the Hilton ADT is traditional and a bit smaller. It has a great Exec Lounge with nice view. The neighborhoods are also different. Both are great hotels. Normally, I would not change hotel in the same town just for 1 night. But if I am curious about the Hilton, then I won’t mind give it a try.

Lugging bags cross town should not be that big an issue (assume you travel light for one week). Do request for an early check-in at the Hilton. Or, you ask for a late check-out at the MR (or have them store your luggage). Go out and do the town as you would. Call the Hilton to ensure room is ready before going cross town.

As I assumed that you travel light, then go cross town by subway is the way to go (fast and save $). Here is the logistic: Coming out of the Marriott RG front door, turn right and walk 4 minutes to Glaciere Station (Metro Line 6, in direction of Charles de Gaulle Etoile). Take the metro train to Trocadero Station; change train to Line 9, direction Nation. Four stops later, alight at Saint-Philippe du-Roule. Before exiting the underground, look for a map somewhere on the wall and pick the correct exit. It takes only a few minutes walk (north on Ave Herrick Myron and left on Rue de Courcelles) to the Hilton hotel.

Hilton ADT is not that close to the landmark of the same name. One can go to the Hilton by taking the same Line 6 metro train from Glaciere to Charles de Gaulle Etoile Station (final terminus of this line) without a change of train. Right above this station is the landmark Arc de Triomphe. The walk to your hotel is farther than the above route (a short taxi ride if not walking).

I am sure you have checked out Paris Metro map and map of Paris by now. If not just google them.

Have fun in Paris!