Getting to Gare de lEst

I suggest a taxi from your hotel to Gare de l'Est that first morning, your hotel can get one for you. The Metro is generally safe, including late evening. Pickpockets are always an issue on the Metro and at heavily visited sights, but the less crowded it is the better, so 10:30 would be better than during rush hours. You should be fine, have a great trip.

The M4 metro goes to Gare de l'EST in a little over 15 minutes. Surface travel (taxi/uber) could get snarled in rush hour traffic in the morning. 2230 hr is not late by Paris standards. You should be fine

Just to clarify that either option is good. Indeed, the metro 4 goes straight to Gare de l'Est from Saint Germain, but if you aren't comfortable, it's a straight shot for a taxi, too, straight up the boulevards, which were in fact roads laid out by the Romans. The only thing holding up taxis, which have access to bus lanes, is buses pulling over and bicycles. But the taxis can also get into the regular lanes and pass.

Hi, what day of the week will this be ? There are various early closures of line 4 to be aware of:

On Sundays through Dec 31, the line 4 doesn't start operating until noon.

Wednesday and Thursday nights until Nov 19, the line stops operating at 10:15 pm.

From Nov 21 through Dec 24, the line stops operating on Tuesdays, Wednesdays, Thursdays at 10:15 pm.

No service at all on the line on Sunday October 16.

We did this same trip twice last year, it's easy (but a bit pricey) by taxi. There are taxi lanes so they can go pretty quickly. Also easy by combo of walk and metro, if you are ready for that.

Returning from Gare to Left Bank, there's a line outside the station and you wait for a taxi. Or you could walk away from the station a bit and look for a taxi stand, that's how taxi is done in Paris.

There is also a useful taxi stand outside the St. Sulpice church in SGdesPres I found it simpler to have taxis drop me there and walk to my nearby hotel since it was easier than trying to get them to the hotel itself.

So much good information. It will be on a Friday in December

I’ll add that I suggest you download the G7 taxi app.

If it’s just a day trip ( no luggage) you might see how you feel about the Metro once you’re there. Otherwise book a taxi a few hours before. You can pay thru the app.

On a weekday morning, book your taxi the day before (the G7 app allows that).
EDIT: there are bus/taxi lanes almost all the way from Saint-Germain des Prés to Gare de l'Est, so major traffic issues/blockages are unlikely. I would book my taxi approx. 60-75 minutes before scheduled train departure (Gare de l'Est is very straightforward, tracks are all side by side in the same shed). To me, it beats taking metro line 4 with luggage in the AM rush hour!

Be sure to allocate enough time for the trip. I've missed trains twice in Paris going across town in taxis because I or the hotel front desk person who arranged the taxi did not allow enough time for traffic.

cross town in a taxi is always a craps shoot; traffic can really delay things; we have had cross town trips take twice the time expected. I'd take the metro unless it is disrupted for renovation or something.

Thank you all!!!