There are lots of restaurants on Rue de Grenelle and Rue Saint-Dominique which are at either end of the street where your hotel is located and between you and the Eiffel Tower. I like Cafe Roussillon on the corner of Rue de Grenelle and Rue Cler. I do see you didn't want to eat on Rue Cler until later. This is across from the end of the block with the market area. You may wind up walking thru the Rue Cler several times anyway. My favorite gelato place is Amorino at the far end of Rue Cler from where you'll be. To me Rue Cler isn't really a destination, it's more of a neighborhood. Others will have their opinions.
I would be totally put to sleep by riding on a bus thru town for several hours but it may work for you. I also don't like to be that far from the hotel on the first day. When I crash, I crash and might need a quick nap in the afternoon.
If the day is bright and you have an interest in Art Nouveau architecture, you might just want to wander around the neighborhood a little bit, loosely following the stops suggested on this self-guided walking tour. It goes by buildings designed by Jules Lavirotte. Starting at the location listed at the end of the tour puts you at a set of doors that are literally at the end of your street and a few doors right/west. (I can't tell you how aggravated I was myself when I realized how many times I had walked by these doors and had not looked at or noticed them! They are neat!)
https://www.parisperfect.com/blog/2011/03/art-nouveau-7th-arrondissement/
I also like to make one of my first sights the Eiffel Tower so you could also consider walking over there. Really, seeing it more than once is OK!
You are also just a couple of blocks from the Seine so you could walk down there, walk along in either direction and enjoy the area.
Will you have any Euro with you? I usually start with 200 from home (now left over from prior trips but to begin with from a local bank) but others are fine with no cash on hand. I don't want to have to deal with an ATM jet-lagged so that's why I do it that way. If you don't have cash, I'd stop to get Euro at CDG. You can buy a carnet once you get to your hotel. You are not far from the La Tour Maubourg Metro stop which I ~think~ has manned windows where you an buy a carnet. They do have ticket machines. There is definitely a manned window at the Ecole Militaire Metro stop but that's a few blocks down Rue Cler to get to it.