Don't worry about getting lost, that happens to many of us ;-).
For starters, I am just presuming that are you planning to make (almost) all your trips in the Bernese Oberland and that are you leaving Switzerland again through Basel EuroAirport. If my presumptions are wrong, please let me know.
All mentioned prices are second class and per person.
Option 1: A Swiss Card
, covering Switzerland.
The trip from Basel EuroAirport to Lauterbrunnen will cost you CHF 66 for a single ticket or CHF 132 for a return ticket.
The Swiss Card (valid one month, travelling for half price almost anywhere, free travelling on your first trip from and last trip to Basel EuroAirport) would be CHF 182.
A Swiss Half Fare Card
, valid one month - travelling for half price almost anywhere, would be CHF 99.
You would save CHF 132,- (transfers Basel-Lauterbrunnen-Basel) with a Swiss Card, and this is more than CHF 83, the price difference between the two mentioned cards.
If you purchase a Swiss Card can view the area of validity
, please note that you will get a 50% discount on your trip to Schilthorn and a 25% discount on (between Wengen and Jungfraujoch) on your trip to Jungfraujoch.
Option 2: The Regional-Pass Bernese Oberland
, covering the Bernese Oberland.
This pass does not cover your transfers from and to Basel EuroAirport, but will give you a 50% discount on travelling in the Bernese Oberland and 3 days of your choice (Pass for 7 days) or 5 day of your choise (Pass for 15 days) of free travelling by trains and cog railways, gondolas and cable cars.
The price difference between a 7-day Pass (CHF 230) and a 15-day Pass (CHF 277) is not too much, and the extra two days of free travelling might be worth the price difference.
With this Pass you will get a 50% discount on your trips to Schilthorn and Jungfraujoch.
Option 3: The Jungfrau Railways Pass
, covering the Jungfrau Region.
With this Pass you will have unlimited travel on 6 consecutive days in the Jungfrau region
and you will also get a 50% discount between Eigergletscher and Jungfraujoch, but no discount on your trip to Schilthorn. This Pass will cost you CHF 200.
This is the best I can do for you, as I don't know which means of transportation you are planning to use on your trips, but I am rather sure these are the best options.
I can tell you that I have been happy with the Regional-Pass Bernese Oberland for many years, but that does not mean it will work for you. Viewing the links I gave you may help a lot, and there's always the Railway FAQ
Wishing you lots of fun in Switzerland, and please get back to me if I can be of any further help!