Lyon or Saint-Malo?

This is Saint-Malo's strength. Lyon is inland, about three hours from the Mediterranean, so swimming means the supervised lake at Miribel-Jonage or a day out to Annecy or the Lac du Bourget. In summer those Alpine lakes are actually warmer than the Channel.

Saint-Malo has the Grand Plage du Sillon and coves such as Bon-Secours right below the ramparts, along with a seawater pool that stays full at every tide. At low water the beaches double in size. The sea is chilly, so you will spend more time on the sand than in the water, but in July and August it is a proper beach town.

Lyon is one of France's great eating cities, and the gap here is wide. It has bouchons serving quenelles and andouillette, Les Halles Paul Bocuse, a fine-dining tradition that goes back to the Mères lyonnaises, and the wines of Beaujolais and the northern Rhône.

Saint-Malo's cooking is narrower and simpler: galettes with cider, salted-butter caramel and seafood, with the oysters of Cancale as the highlight. Its weak spot is the many tourist crêperies inside the walls. In Lyon, tourist menus are mostly limited to one street, the rue Mercière.

Lyon covers two thousand years of history. There are the Roman theatres and Gallo-Roman museum on Fourvière, the traboules of Vieux Lyon, the Musée des Beaux-Arts and the Institut Lumière, enough for several full days.

In Saint-Malo, most of the sightseeing is one walk around the ramparts of a granite town rebuilt after 1944, with the cathedral and castle along the way. At low tide you can add the island forts and Chateaubriand's grave. The corsair history gives the town atmosphere, but it fills a day rather than a week, and there are no major museums.

Lyon is far livelier after dark. Wine and cocktail bars crowd the Presqu'île, barges on the Rhône serve as bars and clubs, and there is a real electronic music scene towards Gerland and the Confluence. Outside weekends and term time, though, nights end earlier than you might expect.

In Saint-Malo, an evening means a drink in a pub or wine bar inside the walls, and only summer weekends run late. For clubs, people go to Rennes.

The two are close here, but the landscapes are very different. Lyon's outdoors is rivers and hills: running and cycling on the Rhône quays and boating in the Parc de la Tête d'Or. With a car you can reach the Monts d'Or, the Beaujolais and the limestone massifs of Chartreuse and Vercors, and the high Alps are about two hours away.

Saint-Malo is all coast. The GR34 path runs east to Pointe du Grouin and west to Cap Fréhel, and the tides rise by up to about 13m. Instead of mountain hiking and climbing, you get kayaking on the Rance, sailing in the bay and kitesurfing on the long beaches.

Both make excellent bases, with different themes. From Lyon you can reach Roman Vienne, medieval Pérouges, the Beaujolais villages, Burgundy around Beaune and the lake at Annecy. Wine and old towns are the main threads, and Vienne is only a short train ride away.

From Saint-Malo the big trip is Mont-Saint-Michel. Half-timbered Dinan, Dinard across the estuary by boat, Rennes by train and summer ferries to Jersey round out the choice. Most of these are much easier by car.

Both are safe and easy with children, but the days look different. In Lyon they centre on the Parc de la Tête d'Or, with its free zoo, pedalos and little train, plus dinosaurs at the Musée des Confluences, Guignol puppet shows and the funicular up Fourvière.

Saint-Malo is a beach-and-ramparts vacation: sandcastles, pirate stories, the sea pool and walks out to the island forts, with the Grand Aquarium for wet days. There, parents need to watch the fast tides. In Lyon the challenge is the steps of the hills with a pushchair.

Lyon is easier to get around without a car. The flat Presqu'île is good for walking, and the metro, trams, funiculars and bike-share cover the rest. A tram also runs to the airport.

Saint-Malo is compact enough to walk, with buses to Saint-Servan and a passenger boat to Dinard. The coast beyond the town and Mont-Saint-Michel have only thin bus services, though, so once you leave town you will need a car or a tour.

Lyon gives shoppers more to work with. There are chain stores along the streets of the Presqu'île, luxury labels around Place des Jacobins and the large mall at Part-Dieu, plus silk from the city's weaving past and designer boutiques on Croix-Rousse.

Saint-Malo is mostly souvenirs and Breton specialities: striped sailor tops, salted butter and caramels, faience and marine prints. For fashion or department stores, visitors go to Rennes.

Neither is cheap, and overall costs are similar. In Lyon, hotel rooms get expensive during big trade fairs and the Fête des Lumières in December, and set lunches in bouchons are the best value.

In Saint-Malo, prices follow the season. Rooms near the beach are dear in July and August and seafood platters add up, but galettes are cheap and spring and autumn are noticeably cheaper.

Lyon has a stage season that runs through most of the year, while Saint-Malo mostly has a handful of festival dates. The glass-vaulted Opéra houses a resident opera company and ballet, the Orchestre National de Lyon plays at the Auditorium near Part-Dieu, and the Célestins is one of France's grand old playhouses. Dance is the city's speciality, centred on the Maison de la Danse. In summer, the Nuits de Fourvière puts concerts and plays in the Roman theatres above the city.

Saint-Malo's town theatre runs a modest programme of touring plays and concerts, with the occasional organ or chamber concert in the cathedral. Its year turns on festivals: La Route du Rock for indie music, Étonnants Voyageurs for books and Quai des Bulles for comics. Plan around those dates, because on most other nights there is little to see, and for opera you have to go to Rennes.

Saint-Malo is the better place to unwind. Its seafront thalasso centre, with heated seawater pools and hydrotherapy, belongs to a long French tradition it shares with Dinard, and outside August the town is calm.

Lyon has no bathing tradition, only a few hammams and day spas and the open-air pool on the Rhône quays. Relaxing there means long lunches and quiet Sunday mornings by the Saône. For thermal baths you need a day out to Aix-les-Bains.