Lots of good suggestions...locally, just find long & steep and push yourself up it, then go for altitude acclimatization in the Sierra closer to summit time as weather allows...then make sure you have a good block of time at 10K+ altitude immediately before the actual attempt, and bring Diamox anyway.
Half Dome is open early which makes permits easier to come by, if late-season snow doesn't ruin your plans. You can do that as a dayhike for 4800' and some early elevation exposure. Clouds Rest from the valley is longer/higher, but no permit required...can do from Tenaya Lake as well, but it's a cakewalk.
Mt. St Helena via Oat Hill Mine/Palisades is a good climb
Berryessa Peak:
http://www.yolohiker.org/trails/knoxville/BPT/index.htmlI like the Mitchell Canyon side of Diablo...head up Cardinet, Olympia, East/Zippe trails and make a 3-5 peak circuit among Olympia, North, Diablo main, Eagle & Twin. Trails mentioned, along with the short North Peak access road, border on insanely steep.
Also in Diablo east-side area: Las Trampas preserve. If there's a mile of flat trail here, I haven't found it. Opportunities for self-inflicted ass-kickings abound here.
Henry Coe SP (don't confuse with Henry Cowell) is far but a real jackpot for training--in fact I sometimes feel Mt Whitney is good training for Coe. The Mt. Sizer shortcut up Hobbs Rd from Middle Fork Coyote Crk is the most infamously brutal jeep-road grade: something like 1500ft in 1.2 miles. Doing anything substantial (Sizer, e.g.) from park HQ (2600' elev) will require coming back up a long grade like Poverty Flat at the end, which adds a lot of suffering on a hot dry afternoon when you're already tired. There are other worthy climbs, like Steer Ridge or Middle Steer Ridge to Mt Willson via the more accessible and low-elevation Hunting Hollow entrance. Bear Mtn Road is also murderously steep in places. Possibilities abound for 15-25-mi loops--Kelly, Coit & Missisippi lakes; Pacheco Falls, China Hole/Narrows, Rockhouse Ridge...
Uvas Canyon: "Knibbs Knob" is a sandbagging name for a tough climb.
Pinnacles Pig Fence: on a hot day, break out the heavy gardening gloves and hike North Chalone Peak via the "pig fence", then drop to the reservoir and hike the High Peaks loop. If you're careful the barbed wire fence of the Chalone ascent won't cut you, but it will hurt: something like 2500' in 2 miles as you cling to the fence up the 35-40% pitches.
Mission Peak from Stanford Ave--mentioned already, but take Peak Meadow/Horse Heaven route to go even steeper and avoid crowds. For bonus, descend backside to Sunol and then come back for double elevation. Monument/Allison from Ed Levin is a variation on the same theme...steep, hot, & [sun]-exposed
Ohlone Wilderness Trail from Del Valle thru Williams Gulch & up Big Burn to the Schlieper Rock/Jonny's Pond area will have you swearing...continuing on to Rose or Murietta Falls is optional for distance.
Black Mtn (2812') in Los Altos (Rancho San Antonio starting from Rhus Ridge trailhead off Moody) is 2300' in just under 5 miles for a 10mile out/back.
Montara Mtn from Gray Whale Cove is fairly steep if you take the use trail shortcuts...popular workout, but I don't find it all that challenging.
Priest Rock from Lexington Reservoir: 2000' gain in an 8-mi out-and-back... scrubby, hot & uninspiring.
Cone Peak via Sea-to-Sky: Drive down to Limekiln St Park near Lucia, dip a toe in the Pacific, then head up the old Twitchell Flat road from Hwy 1 to the base of Stone Ridge, then go straight up the use trail to Twin Peak then Cone Peak. Come back down same way and try not to fall! Trekking poles recommended. That's about 6000' in 6 miles and it's as painful as it sounds...glorious views, though.
One practical suggestion, join a group like INCH or the San Jose, Sonoma/Marin long distance, and Monterey hiking meetups. These all do long, hard hikes at >3mph pace, at least with particular organizers. Be forewarned that many other area meetups will often hike very slowly, taking long breaks and waiting around interminably at trail junctions for laggards, none of which is optimal for MW training.
