I ended the daily public transport strike update which ran for 3.5 months. There will always be protest and transport strike risks. Some ways to hedge:
1) Metro 1&14 are strike-proof and most tourist sights are on M1 line. Consider lodging near Metro 1&14, except M1 stations on Champs-Elysees (often closed due to protest and crowd gathering events). Chatelet is the most convenient public transport hub (M1/4/7/11/14, RER A/B/D, dozens of bus, Disney shuttle). République is the most protest-prone location (often metro/streets/shops closure).
2) From CDG to Paris when SNCF or RATP is on strike -- skip RER-B, take Le Bus Direct to connect to M1/14 @Etoile-Champs Elysees (M1), @Gare de Lyon (M1/14). Roissybus works if lodging is near Opera. Opera is not a M1/14 stop and it has many flights of stairs, M14 Madeleine is 5-min walk from Opera (FYI -- average 4-6 flights of stairs per metro station. Only RER stations and M14 stations have elevators/escalators)
3) Official taxi are not allowed to charge more during strike. Know the Airport-City taxi flat rate. Uber is known for unpredictable "surge charge" during transport strike.
4) It is financially more feasible for SNCF/RATP workers to strike in December/January b/c they receive 13th month pay in December. To visit Strasbourg/Colmar Xmas markets, safer to fly in/out of Frankfurt Airport and take the Lufthansa Frankfurt Airport-Strasbourg Express Bus.
5) Direct SNCF TGV and Deutsche Bahn's ICE run b/w Frankfurt main train station (Hbf) and Paris Gare de l'Est, and Paris-Strasbourg-Stuttgart. Need 1 easy train connection if from/to Frankfurt Airport. Both TGV/ICE bookable on both DB/SNCF sites -- if ICE/TGV booked from DB site is cancelled due to SNCF strike, DB $ refund is prompt/easy and DB allows taking a same-day alternative ICE without re-booking (take any open seat or sit in restaurant car). Re-booking is required if TGV/ICE ticket is bought from SNCF. To get $ refund from SNCF needs extra effort. https://www.bahn.com/en/view/index.shtml.
5) Consider long distance buses Euroline/Isilines/Flixbus as back-up (not SNCF's Ouibus)
6) CDG/Orly Airport real-time road condition & public transport info -- https://www.parisaeroport.fr/en, click on ACCESS.
7) For drivers -- French government info for real-time traffic status/forecast, weather/road condition (in English) https://www.bison-fute.gouv.fr/index,langen.html
8) Local transport strike affects monument/museum opening/closing time because staff can't get to work. Check in the morning the web site/twitter of monument/museum you plan to visit.
9) To monitor strike/protest:
--Good resource site listing all CURRENT & UP-COMING STRIKES in France https://www.cestlagreve.fr/ FYI -- work-stoppage often starts in THE EVENING BEFORE the declared strike day, and lasts into early morning hours THE DAY AFTER the declared strike day. Stoppage time info is in the strike notice filed by the unions (search words: union's name & "Préavis de grève")
-Useful search words to find FRENCH MEDIA REPORT RE UP-COMING & CURRENT TRANSPORT STRIKES: "SNCF, RATP, syndicat, grève, aéroport, transport aérien, pilot". I find strike info from Linternaute.com the most up-to-date/comprehensive and easily readable on Google Translate. English-language media reports usually appear either right before or after strike started.
-Good resource site to find all PARIS PROTEST/DEMONSTRATIONS (with detail/route map/time/meet-up points) -- https://paris.demosphere.net/
*The official approved time/route is typically confirmed the afternoon before!
*The meet-up time/locations ("rendez-vous") info show where/when crowd will start gathering many hours before the official protest, typically confirmed the evening before.
*Yellow Vest protest = "Manifestation à Paris des Gilets jaunes" (usually on Saturdays)
*Anti-pension reform protest = "Manifestation à Paris pour les retraites"