Hi Avawda- I've looked through the thread, and find that a couple of useful links were not provided directly. They'll help a lot with the place names, and also with the times that the public transport facilities in the Jungfrau region open for the summer season.
By the way, the names are not in Greek, they are in German. ;-)
Με την ευκαιρία, δεν είναι στην ελληνική, είναι στα γερμανικά.
Unfortunately, as Maggie noted, many of the scenic options in the Jungfrau region are closed between the winter skiing season ( ending roughly at the end of March ) and the Summer season (opening some in very late May and early June and mostly open by June 15th.
What is open depends a lot on altitude. Luzern will be enjoying Spring weather at around 400 meters. For a related example, the high mountain pass roads above 2000 meters do not open until early June, as a rule. They are covered with deep snow. Wengen, at 1300-1400 meters will be pretty much snow free.
For details in a very powerful map, which I have shown without hiking trails turned on, I use the Federation's official SwissTopo site. There, you can see the altitudes, and a lot more than you might want:
map.geo.admin.ch/?topic=swisstopo&lang=e n&bgLayer=ch.swisstopo .pixelkarte-farbe&layers=ch.swisst opo.zeitreihen,ch.bfs. gebaeude_wohnungs_regi ster,ch.bafu.wrz-wildruhezonen_portal,c h.swisstopo.swisstlm3d -wanderwege&layers_visi bility=false,false,fal se,false&layers_timest amp=18641231,,,&X=1625 20.00&Y=636580.00&zoom =6
I showed the map with the hiking trails turned off in that link..
The Lauterbrunnen Valley is at 700-800 meters. May is fine, although the deep valley does not get a lot of sun, and there may still be traces of the last bits of snow. Männlichen ( about 2229 meters), Männlichen Gipfel ("summit" or "peak" )at 2343 meters and the excellent trail to Kleine Scheidegg (about 2000 meters) are not accessible for hiking until sometime in late May, more likely early to mid-June. There is one place on that trail which is snow covered late in the Spring, due to angle of the sun and shade. Although it could be done with an infant in a stroller or some form of wheeled device in the summer, I'd not recommend it, even after it is open. You'd enjoy the views but not the work.
If you choose to visit Jungfraujoch, at around 3400 meters, you might check with your doctor about the appropriateness of those high altitudes for young children.
I've attached a couple of pictures to show why you should come back in the Summer or early Fall. ;-)
You can determine what transport is open by checking specific routes in the time table on a day that you choose.
I do not agree with Bouboucadeau's comments-
<<" i came back from 9 day switzerland trip back in february. i did lucerne for a day trip.. small town with little sights to see, Lake Lucerne, old town Wall, old town, .. if you wish to see Mt. Rigi , maybe you can do 2 days in lucerne..">>
In my opinion, you could spend a week in the vicinity of Luzern (that is the German spelling, and what you will see on signs in the area) and have plenty left to see and do. His visit in February restricted some of his options.
I took the attached picture at dawn on an unusually clear day in June, from the old town, in the Hotel Schiff (now closed, unfortunately)
In the old town, a walk around is enjoyable.
The Lion of Luzern is justly famous. The image shows my then 8 year old granddaughter on a page taken from a photobook that I prepared in 2009.
My friends and family of all ages enjoyed the Bourbaki Panorama near the Lion.
Your child is probably a bit young for the Transport Museum.
A lake boat ride to Vitznau and a cograil train ride to Rigi Kulm , followed by a return via various routes is very scenic.
The two or three pictures attached related to Hammetschwand are mainly to show the environment. There is a bit of a walk to get up to Hammetschwand, and the current public transport connections are difficult due to construction at the hotels up there. The trail to the base of the outdoor elevator is smooth enough for wheel chairs, but the reward for effort might not be something you'd like to try with an infant. If you would, i can provide more details.
I also believe that Bouboucadeau did not take the time to dig into Zürich. It is my favorite town in Switzerland, but it does require a a few trips to really appreciate it. And, the attractions are more cultural than scenic. Some splendid museums, for example. However, for the first time tourist. Luzern is much more rewarding, with a variety of easily accessible attractions. Luzern is a 45 minute train ride from Zürich, twice per hour.