easy hiking daytrips from Geneva, Lausanne and Bern

If you take a train (national railways) to Nyon, then change for the (private) mountain train Nyon-St Cergue- La Cure,
Get off at St Cergue or further up, you have nice downhill trails through the forest, meadows, then vineyards, overlooking the lake, with the whole Alps in front of you. you can avoid the town entrance by getting back on the train.
Timetable and info here...

hi istvan
from berne, many possibilities. for all public transport, look at www.sbb.ch for time schedules etc.
for hiking suggestions, look at http://wanderland.myswitzerland.com/en/wanderland.html (enter the point of departure to get some suggestions).
- thun (20 minutes by train) and spiez (30 minutes by train) are great for lakes, mountains, views. if you read german (and even if you dont, you cant get ideas there), check out http://www.wandern.ch/de/wandern/unsere-wandervorschlaege?&id=703 or http://www.wandern.ch/de/wandern/unsere-wandervorschlaege?&id=807.
- another nice and easy hike in the thunersee region is the "höhenwanderung" from heiligenschwendi to schwanden oder sigriswil http://www.wandersite.ch/Tageswanderung/710_b_Bern.html . heiligenschwendi (travel via thun) is on 1100m, and the short hike offers great views over the lake
- another idea is to take the train to solothurn and hike along the aare river to büren an der aare. from there travel by train to biel, and maybe enjoy a boat trip on the lake (or go for another hike on the bielersee). you could take the boat to the st. petersinsel, and then walk to erlach (a very nice short flat walk), and return to berne from there
- around the bielersee, plenty of possibilities, for example http://www.bielersee.ch/de/region-ausfluege/ausfluge.152
/twannberg-wanderung-panorama-tour.518.html
- of course you can also start hiking from berne (or very close to it), along the aare river. if the weather is good, you could combine the hike with a swim in the aare river, a meal in a scenic restaurant and / or a ferry ride over the river. look at schloss reichenbach or zehendermätteli if this appeals to you.

As Nathalie told you, there are tons of possibililties from all 3 towns. It's absolutely impossible tolist them all. Don't forget that Switzerland has more than 60000 (sixty thousand) km of well signmarked hiking trails.

Around Geneva, there are tons of combiniations with the Mount Saleve cableway, the La Cure railway and the buses from Nyon through the vineyards to the Jura heights.

Around Lausanne, check the Lavaux vineyard trails, the trails between Blonay - Les Pleiades, Cubly - Sonloup - Les Avants and Caux, the trails between the Yverdon - Ste Croix railway and the Grandson - Couvet bus, the trails in the vineyards around Aubonne - Signal de Bougy .........

If you want to be in front of the highest mountains of Switzerland, take a train from Lausanne to the Crans-Montana hiking area or from Berne to the Riederalp-Aletsch Glacier trails.

hikes from lausanne:
i second merckerdv, definitely go for a hike in the lavaux vineyards. the vineyards and the lake, and a sunny day = extremely beautiful. if you like wine, you should also include a visit to a cellar. look out for "cave ouverte" (open cellar).