Day trip from Paris

Taking the Eurostar is the fastest way to get to Paris (from Gare du Nord) from London (St. Pancras station) and vice versa, which we did just last week. This is the best time to check for fares for your October trip. They do increase as the time goes by. Taking the train/tube is the best way to go around these 2 big cities because of traffic.

We went to Monet's House/Garden at Giverny. Not too long of a drive. I am not sure how to get there by commuting. I tried typing it on Google Maps, but it did not show anything for bus/train commute. From the parking lot though, the walk to the attraction was really nice. There were some bed and breakfasts that you walk along the way (in or) out and a hilltop that you could enjoy marveling at!

Anything outside the city of Paris and London would for sure be good for what you're trying to do. In London, we checked in at Kensington High Street. It depends where you're going towards to, but there's a good mix of residential and commercial places that you could enjoy walking in.

For Paris, our cousin lives in St. Germaine, which is outside of Paris. It was definitely a good experience for us to see how and where locals live. You could see people, young and old, waiting at the bus stops. Or relaxing with family and friends at the cafes.

You can get to Giverny from Paris by train and bus, but it will take much longer than driving. Fontainebleau and Chartres are easier to reach by public transportation. Consider also Orleans and Reims, if you have the budget.

From London, consider day trips to Hampton Court palace, Kew Gardens, and Windsor. They're all technically part of the greater London area, but fit the day-trip description. I also recommend the day trip to Oxford and Blenheim Palace (in nearby Woodstock).

Reims is a great day trip by train, with beautiful cathedral, champagne tasting, and important WWII sites.

Monet's Gardens in Giverney is easy to get to by train (there's a bus waiting outside the train station to take you to the gardens), and it makes a great combination with Rouen, although you could just enjoy the day in Vernon and Giverney. A trip to the cathedral in Chartres.

I haven't been, but next on my to-go list is Auvers-sur-Oise, where van Gogh worked and sadly, died.

For quaint and cute, Provins is a lovely medieval town. Easy and cheap to reach by train from Paris, if a bit long (about 1.5hr)

Take a look at Moret sur Loing and Crecy la Chapelle and Senlis here.
https://janettravels.wordpress.com/category/day-trips-from-paris/
Conflans Honorine was not bad either as we enjoyed the walk along the Seine and lunch at a little restaurant on an island along the way.

hey hey kristine
we are taking a train to andresy to have lunch at la goelette and walk along the seine as janettravels44 suggests. (thanks janet)
couple years ago we took train to reims, walked from train station to town, had lunch and great local champagne at an outside cafe/restaurant. after that we had a tour in a 2CV thru town and into the vineyards. stopped at private "cave" with tastings. was a great tour for us. the big name "caves" were so crowded we decided to walk around the center, see the cathedral, shop a little and sit at cafe for more local champagne and people watch. train bacl to paris later that afternoon. we bought roundtrip tickets day before so no waiting.
in london we went to "little venice" on our way to abbey road. (walks.com)
jasons.co.uk (a barge ride up the regent's canal)
streetsensations.co.uk (london markets map)
sussexbloggers.com (check out the town of rye, east sussex)
aladyinlondon.com (day trips and walks in or around london)
b-bakery.com (afternoon bus tea ride thru central london and seeing main sights)
whatever you decide have a great vacation, you'll love it. lots to see and do.
since you are traveling between london and paris, buy your eurostar ticket early (3-4 months out eurostar.com) for cheaper tickets. check arrival times to either city, do you have early checkin or luggage storage)
aloha

I think Imee is referring to the town of St Germain-en-Laye. Very nice town just a few miles outside Paris and super easy to get to on the RER. Has a famous chateau, good cafés/restos, fun shops.
Not touristy at all.

Thanks every one. Some great suggestions.

I was pleased with Chartres as a day trip.

http://www.minorsights.com/2016/03/france-senlis.html

Years ago I found one company offering a one-day trip to the Normandy. D-Day sites. Yes, spending a night in Normandy is a much better idea if one has the time. But at the time, that was not an option, and I am so glad that I went.