Hi Henry G
My wife and I also in our mid 60s have stayed in Wengen and hiked Bernese Oberland area several times and here are some suggestions along with some photos to give you a sample of what you can expect to see.
First to Bachalpsee to Waldspitz(this section is my personal favorite) to Bort, then cable car back to Grindelwald. rated 2.40hrs hiking time without stops
First to Grosse Scheidegg then bus back to Grindelwald rated 1.25hrs
Männlichen to Kleine Scheidegg(1.2hrs) then KS to Eigergletscher(1.00hr uphill) train back down to KS to avoid moderate downhill then we walked from KS to Wengernalp(2.0hrs, mod downhill) then train to hotel
The Eiger trail. Eigergletscher to Alpigen(downhill) rated2.50hrs
Lauterbrunnun valley. Lauterbrunnen to Stechelberg then back to Lauterbrunnen by bus. Flat easy walk:the rating not given on my map but about 1.5hr as I remember it. Instead of return by bus can take gondolas up to Schithorn and gondola, train ,and cable car back to Lauderbrunnen.
Schnynige Platte. Probably the most stunning views of all. Take the panaramaweg trail from train station. Along the way climb steps to Oberberghorn lookout. The trail is a cliff top walk with Jungfrau,Monch,Eiger,Manlichen, and Lauderbrunnen valley on one side and Brienzersee, Interlaken, and Thunersee on the other side. Route rated 2.30hrs.
If your really adventurous and fit. First to Schynige Platte (or reverse route) is classic but strenuous with steep climbs to Faulhorn. Rated 6.30 hrs.
Note hiking times are approximations and don't include stops. Restaurants with outdoor seating for lunch or a quick beer are available at First,Waldspitz,Grosse Scheidegg, KS.,Alpigen,Schynige Platte, and Stechelberg.
We found Wengen to be a good base. Its more scenic than Lauterbrunnen or Grindelwald and more convenient than Murren for connections to hiking trails. Mark