I am getting ready for my first backpacking trip in Yosemite Wilderness in mid-September. I've hiked Half Dome twice before and gone on one 8-day backpacking trip previously, so I consider myself very experienced hiker and a fairly experienced backpacker.
I am looking for (1) suggestions on 3-5 day itineraries and (2) thoughts on reasonable daily mileage.
It really depends on what you prefer for your trip (waterfalls, views, etc). There are many great trips in the Yosemite area. For a 3 day itinerary the Mist Trail to Little Yosemite to Sunrise Creek and out to Tenaya Lake via Clouds Rest is pretty hard to beat. The North Rim is a good route that you can stretch into 3-5 days. Glenn Aulin is beautiful and you can easily do 5 days by going into the Northern area from there. As far as a reasonable daily mileage that is entirely dependant on your abilities and desires but I would plan for about 10 miles per day depending on the terrain. Cheers and enjoy your trip!