<<"I wonder though about going directly to such high altitude. Neither of us has ever experienced altitude sickness, but it has been more than 20 years since traveled to any mountainous area.">>
That is a legitimate concern, and, in fact that would have arisen at some point as we discuss hikes.
I thought about it while writing earlier, but forgot to include it.
To convert the qualitative "high altitude" to quantitative numbers - which are given as M.u.M on all the maps in the German convention ( unless, as Peterli will point out, you are in the French-speaking area........). M.ü.M is "Meter über Meer" - which translates as meters above the sea (level) . "m" for short.
A meter is approximately 39.4 inches....about 10 % more than a yard.
Paris - 35 m
Basel - 270 m
Luzern - 435 m ( most of the Swiss lakes are at roughly 400 meters)
Interlaken - 563 M
Lauterbrunnen - 795 M
Wengen - 1274 m ( about 3/4 of a mile).
Männlichen - 2230m about 1.3 miles
Kleine Scheidegg - 2061 m
Schilthorn - 2970 m - 9740 feet
Jungfraujoch - 3572 m - 11720 feet.
Typical cabin pressurization in Boeing 767 and many other airliners is equivalent to 7,000 feet. About 2130 meters.
I don't notice any effects when I walk from Männlichen to Kleine Scheidegg soon after arriving.
However, if I try to climb up the peak ("Gipfel" ) at Mänlichen going up about 100 meters above the Männlichen lift station, I find that I pant a lot and have to pause to catch my breath. It is a pretty steep climb.
If you are worried about it, you could get used to the altitude in stages. Easy stuff the first day or two. Walk first on the valley floor from Lauterbrunnen 795m to Stechelberg 910m ...nice almost level walk with the waterfalls on the cliff walls to look at.
Then, ride up to Mürren from Stechelberg and walk back to Grütschalp, thence the cable way down to Lauterbrunnen. M to G is a bit downhill -1638 m to 1486 m. (Although, I prefer to walk in the other direction, so I look at the Jungfrau massif as I walk toward it).
Or, do it all in the reverse direction, using the cable car from Lauterbrunnen up to Grütschalp to start out.
You can also walk around Wengen and nearby to try that less than one mile high altitude. Then, ride up to Männlichen and walk to Kleine Scheidegg. It is an easy mildly down hill walk (2230->2061m) , with a few very short moderate ups and downs.
If that goes well, you should be OK.