Berner Oberland Itinerary

First, I think you or your autocorrect meant to say "Grindelwald" and not Grunewald. Spelling is important when you get tickets or you may end up in Gimmelwald, miles away from Grindelwald.
If you only have 4 days, I wouldn't go up BOTH to the Jungfraujoch and Schilthorn. I'd pick the latter, espec. since you want to hike down, plus there's too many good trails to explore instead of spending half your time on mountain tops. Speaking of hiking down, know your limitations. Hiking down sounds so easy, until an hour in and your shins start aching like crazy. It's not just an age thing. I walked down with my 14 yr. old from Kleine Scheidegg to Wengen. It looked like a nice 1.5 hr downhill walk, but we both had aching shins. So my advice is to hike down not from the Schilthorn, but from Birg to save your legs a bit.
As for biking, there are certainly bike-authorized trails in the area, and the Tourist Info office in Grindelwald should have a map of such. I've seen it before. I know Rick Steves shows renting a bike (I think in Murren) and it is on one of his free videos on this site. However, here's something to consider: the scenery here is the BEST in the world, so I'd rather spend the majority of my time looking up and around and taking pictures. When I ride a bike on a trail I spend the majority of my time looking DOWN for stones or ruts or whatever to make sure I don't break my neck. So I prefer walking (at least HERE) to riding. You mention biking between Grindelwald and Lauterbrunnen, and I suspect you can, because there is a road and trail between the two. But I would never take it, because you will be out of sight of the mountains--you'll just see trees and a stream. If you were there 2 weeks, ok, but given just 4 days, I wouldn't spend any time away from the fantastic panoramas, unless they were fogged in.
You mentioned hiking, and here are the best hikes, in order from best to still very good.
1. Mannlichen to Kleine Scheidegg, about 1.5 hours. Save for the best day.
2. Schynige Platte to Bachalpsee to First to Grindelwald (last leg via cable car). This takes 6 hours so leave early since cable cars stop at 6pm. If you don't have that time, or weather is iffy, then go Grindelwald to First (cable car) and take the 45 min walk to Bachalpsee (Google image it).
3. Lauterbrunnen to Grutschalp (via cable car) then walk to Murren. From Murren you could go up to the Schilthorn, but check first if the mountain top is fogged in. There's a tv monitor in the Murren cable car station that shows the top. If fogged in on top, you could walk up the trail going up the hill diagonal to the cable car line, and end up at the restaurant and cows at Spielbodenalp.
4. On a dreary day you can walk or take the Postbus from Lauterbrunnen to Trummelbach Falls (Google image it). You can even see those falls in the rain, since they are inside the mountain.

All of this makes more sense when you study the maps:
http://ontheworldmap.com/switzerland/ski/jungfrau/jungfrau-summer-map.jpg

http://www.gimmelwald.com/pics/gimmelwald/hikemap.jpg

Good luck!

Thank you so much shoe! What a great reply, much appreciated. I did mean Grindelwald also FYI. Quick question, we are considering a Berber Oberland Regional pass...would you reccomend this for our 4 days?

Thank you again!

Devin

Yes, I'd probably get that, especially if you are taking trains in/out via Lucerne or Bern, since those routes are about half the cost already. Rick discusses it here:
https://www.ricksteves.com/travel-tips/transportation/trains/switzerland-rail-passes

Thanks shoe! We actually have a car rental to and from airports and to get to to our destination in Grindelwald; thus complicating the decision :S

You might want to rethink the car rental. Most airport cities to Berner Oberland area go thru Bern anyway, and that would be covered by a Berner Oberland Pass. Plus, a car is pretty much useless in the Grindelwald/Lauterbrunnen area. You may be paying $10 or more a day just to park it around there.

I'd also suggest skipping the car rental, as it will likely remain parked for much of your visit, incurring parking charges and gathering dust. Switzerland has an excellent transportation network, and it's very easy to use.

Given the places you plan on exploring in the Berner Oberland, staying in Grindelwald may not be the best choice, as you'll be spending more time and money to get to the places you want to see. The best location in terms of "efficiency" is to stay in Lauterbrunnen, as it's the transportation hub for that area.

Which Swiss Pass to use will be the most complicated part of planning, as there are lots of choices and trying to figure out which one will be most cost effective for the trips you plan to make can be challenging. The Berner Oberland Regional Pass is a good choice, but you could also have a look at the Jungfrau Pass. You may find this helpful - https://www.ricksteves.com/travel-tips/transportation/trains/switzerland-rail-passes

Thanks everyone.

On the car rental, we have the car for travel in Germany & Austria before going to Switzerland. We figured out, overall it will save us time and money to keep it (and park it) for this leg of the trip to get to and leave the Berner Oberland. We also know about the one fee and have included that in our calculation.

Given this - do you think the Berner Oberland Regional Pass is a good choice? And any other itinerary must-do's?

Thank you!

Thanks everyone.

On the car rental, we have the car for travel in Germany & Austria before going to Switzerland. We figured out, overall it will save us time and money to keep it (and park it) for this leg of the trip to get to and leave the Berner Oberland. We also know about the one fee and have included that in our calculation.

Given this - do you think the Berner Oberland Regional Pass is a good choice? And any other itinerary must-do's?

Thank you!

The Berner Oberland Regional Pass is a good idea as it will cover almost all of your transit locally: train to Lauterbrunnen, many lifts, cog railway to Kleine Scheidegg, etc. Park your car and forget about driving for these few days. You have to pay a bit extra for the Schilthorn or Jungfraujoch. I agree with others: do the Schilthorn this time. Maybe the Jungfraujoch "next trip."

We were in the Berner Oberland for four nights and we did the Schilthorn and Jungfraujoch and didn't think it was a problem to fit them both in -- however we spent our time touring than hiking, so I think it depends on how you want to use your time. However, I disagree with the others in that we thought Jungfraujoch was the place we'd tell others to go, if you have to make a choice (but if your priority is to hike down, then Schilthorn is your winner). I thought the views were better, there's more to do, and it was somewhat of an engineering marvel if you think of it being built in the late 1800s (but...it's also more expensive).

I loved the North Face Trail (Allmendhubell to Gimmelwald) going up by the funicular from Murren. It ends in Gimmelwald, and you can see a wonderfull fall on the way (it was a little tricky to find the fall to me). It is an easy, fun, and beautiful hike. I will never forget that one. Also done the Mannlichen to Kleinne, it was easy and spectacular, too