I spent 2 nights (yep, unfortunately that's all) in Gimmelwald (just a gondola ride away from Murren) last June. So I have some comments on a couple of your questions:

The Berner Oberland is a wonderful region - very pretty - even more so when it's not raining! I had one full wonderful day full of alpine gondolas, lifts, and mountains.

A walk (certainly not a hike) that I can certainly recommend is: Taking the lift from Grund to Mannlichen. Be prepared - when I was there in the middle of June Mannlichen was covered in snow! Little ground-hog looking animals, cow bells ringing, alpine flowers peeking through the snow in places. It was then a lovely pleasant stroll for about an hour down to Kleine Scheidegg. As you walk further the snow had melted and we saw more flowers poking through the snow, and the water turned into little riverlets. Not too many flowers alas. But snow and babbling brooks and the odd flower peeking out as we got lower. We stopped for lunch then continued walking down to Wengen. Here we then caught a train down to Lauterbrunnen. It was a lovely train ride with the windows down looking at the chocolate box villages on the hill sides. I didn't walk to the Stummelbrauch Falls from Lauterbrunnen which are supposed to be spectacular. After time in Lauterbrunnen I took the funicular and then the train to Murren. (From where you could walk or gondola back to Gimmelwald.)

I had made some notes from a newsgroup which weren't relevant to my time in the Berner Oberland but I fished out this saved comment: Alpine flowers - Berner Oberland - Schynige Platte provides one of the best views of the Jungfrau massiff. At least as worthwhile but much less-visited, there's a fine, almost unique, alpine garden there. There's a short growing season at this altitude (perhaps 75-90 days) though Alpine flowers of one kind or another will be found between roughly mid-late June and mid-late August. Depending on season many other Alpine flowers in meadows throughout the region.

I was disappointed by the lack of alpine flowers when I was there and your timing may see you on the other side of the season but interesting to note nonetheless.

I would have loved to have made the trip up to the Jungfrau had the weather been accommodating - but I have heard it is very expensive, and it may just be a been-there-done-that kind of attraction for some people - I have no personal experience alas. I believe the ice palace is amazing. I can say that the view of the Eiger, Monch and Jungfrau from the Schilthorn revolving restaurant is spectacular as I was impressed the morning I was there and visibility was next to nothing!

Also, my decade old boots were sufficient for my walks but I didn't have the opportunity for anything too strenuous. I can recommend treating them with a waterproofing spray or similar before departure.

Hope some of this helps :) Megan Brisbane, Australia