6382 posts
Hi Murugan,
With the Swiss Travel Pass, you can travel for free from Lucerne to Grindelwald or Wengen. From Grindelwald/Wengen to Jungfraujoch, you get 25% off the standard return ticket. Generally seat reservation is not required but is possible if you prefer priority boarding. You can find purchase options here: http://www.myswissalps.com/jungfraujoch/tickets
Regards,
Anna
385 posts
Definitely wait until you’re ready to go up. I’ve been in Wengen when clouds were a bit too heavy and Jungfraujoch was socked in. Then several hours later things cleared up. You never know until you are ready to go up.
72625 posts
I would not book in advance. The Luzern – Interlaken express has plenty of capacity – as do the trains to Kleine Scheidegg, or the Eiger Express. If you turn up at your convenience there is always an efficient queuing system.