Given our age and relative decrepitude, we will be certainly be looking at less technical routes. I suspect this probably means third and fourth class peaks, with the occasional touches of short fifth class pitches. In reality, we will be looking at the "standard" route, the "voie normale," the "descent" route, or the "mountaineers" route on the peaks cited below. Also given our lack of speed, stamina, and mental/physical reserves, we will be looking to minimize our daily vertical to about 1500'-3000' of ascent.
To do this, and make these routes, and summits, viable we will look to lifts, huts, pack animals, or a planned bivy to put us in position to complete these routes safely in a day. I think we can agree, that the days of tagging even a non-technical summit like South Teton from the valley trailhead - in a day - are behind us. However, as we March into our mid-seventies, I suspect these outings are likely to be quite adventurous, and at 70+ years of age, will qualify as big days in the mountains Here are some of the things on my list. What's on yours?
ALPS
In Zermatt the easiest of the 4000m peaks (Breithorn, Castor, Pollux), hut to hut on Hohbalmen loop with scrambling ascents of Platthorn, and Mettelhorn, multi-day hut to hut on Europaweg, and easy multi-pitch climbs on the Riffelhorn
In Chamonix the Index traverse, Cosmique Arete (enclosed 2008 picture), Point Lachenal Traverse, Petite Aiguille Verte, hut to hut from Courmayeur to Argentiere, easy multi-pitch routes on Les Gaillands
SIERRAS
Conness "Mountaineers," Tioga Peak, Individual Echo Peaks, Tenaya Peak, 2-3 day hike from Valley floor to Tuolumne Meadows, a single overnight trip from Lundy Lake to Junction campground, descent route on Lone Pine Peak, easiest route on Mt. Sill
TETONS
easy route on South Teton, short and easy 5th class route on Cube Point, Lake Ledges route on Disappointment Peak, east ridge Cloudveil Dome, easy route on The Jaw, Table Mountain, Static Peak, Taylor Mountain, Mount Fryxell
CASCADES
Mt Hood, easiest routes on Three Sisters, Mt Bachelor,
CORDILLERA BLANCA
Urus, Ishinca, Pisco (using pack animals and huts they are easy but all are 17-18,000')