without any further information I will just throw out three options. There is no particular order. Of course you can reverse each route if you want to switch ascent and descent)
1) Happy Isles to Red's Meadow (53.4 miles, 13,417 ft ascent, 9,838 ft descent)
You see Yosemite Valley, pass Half Dome (you might even climb it with some family members), walk thru beautiful Lyell Canyon, see Thousand Island Lake with Mt. Ritter and Banner Peak and end your trip with visiting Devil's Postpile National Monument.
2) South Lake to Florence Lake (48.0 miles, 8,661 ft ascent, 11,529 ft descent)
You hike over Bishop Pass into LeConte Canyon, hike by the beautiful Pete Meadows and make your way up to iconic Muir Hut on top of Muir Pass. Take a couple of steps of the JMT at the north end of Evolution Lake to see the waterfalls from the lake down into Evolution Valley. Continue your journey through Evolution Valley and don't forget to look back when at McClure Meadow - the view is fantastic, especially at sunset. Leave the JMT at Muir Trail Ranch and cross over the San Joaquin River to soak in the Hot Springs in Blaney Meadow for your last night. Finish your trip at Florence Lake (you can even take the ferry across if you want to shorten the hike by roughly 5 miles)
3) Onion Valley to Whitney Portal (43.1 miles, 13,493 ft ascent, 14,370 ft descent)
Climb over Kearsage Pass to the JMT, enjoy the view from the highest pass on the JMT (Forester Pass at 13,200 ft), cross the unique Bighorn Plateau and climb Mt. Whitney, the highest mountain in the lower 48.
3a) Baxter Pass to Whitney Portal (54.5 miles, 19,414 ft ascent, 17,112 ft descent)
If you want to add the beautiful Rae Lakes to option 3.
There are other options that are very popular like doing the Rae Lakes Loop or hiking the High Sierra Trail that overlap partially with the JMT.
Have fun out there!