Jun 21, 2015 - 10:18 PM
in reply to mynameiseyal
<<"We plan to take day trips from Wengen to Interlaken, Grindelwald and maybe Zermatt (if we won't go to Interlaken or Grindelwald), and we don't plan to reach high altitudes (which are not recommended for babies).">>
You will pass through Interlaken on your way to Wengen. You will change trains at Interlaken Ost. Most people do not consider Interlaken of sufficient interest for a day trip more than part of a day. A nearby town with an attractive old city on the river is Thun. You might consider it for a part day trip.
You might also consider Brienz, famous for its woodcarvers, and with a new Woodcarving Museum next to the Jobin store. (admission fee.)
Wengen is 1274 meters above sea level. Some might consider that a high altitude. If you take the gondola car (Luftseilbahn) from Wengen up to Männlichen - usually recommended - you will be at approximately 2200 meters - in my opinion you are definitely at high altitude then.