Staying in San Fran for 10 days in April. It'll be our first visit to the States for around 10 years.
We're planning lots of sightseeing in SF itself plus we intend to stay overnight in Napa or Sonoma.
Are we being unrealistic to try and fit in Yosemite too? How far from SF is it; can we do it there and back in a day or do we need another overnighter?
Are we trying to do too much in a short space of time?
Thanks

Yosemite is not really doable in a day trip it's about 4 hours to the park itself and then about another 30 mins to get inside. It really deserves a day trip at least because even when you are there there's a lot to see. In addition given that it's winter you might need a 4 wheel drive to get around the park at this time of year, it will depend on the conditions when you get here and when you are going of course. Theres a great place to stay just outside the park called the Yosemite Bug though and it's just off the bus route to the park.–

I agree with Hill 16, It is not possible to travel from S.F. visit Yosemite and return to S.F. in one day.
I visited both places in September so can speak with some experience. We travelled by hire car from Monterey which is about 180 miles (4/5 hours) to the Yosemite Bug Hostel previously mentioned, which is a few miles out of Mariposa on the Yosemite Park road. We stayed two nights at the Bug, which gave us one full day in the park itself and we all thought it was fantastic, although I would have to say that whilst we saw the main features, we could only scratch the surface in the 10 hours we had there. After a second night at the Bug we drove on to S.F. which is about 170 miles and 4 hours drive away. I would say that the time we spent was the minimum to receive a flavour of Yosemite which is a truly awesome place. I would therefore say to you that if at all possible go there, you'll love it. But I would recommend a two night stay at the Yosemite Bug which is a superb place in itself comprising of a series of what outwardly appear to be just log cabins, but inside the ones we had were excellent, with each room having two queen size beds and en suite facilities, and a veranda where you could watch the squirrels and woodpeckers at close quarters in the woodland setting it is in. All for £47 per room per night.
They have their own website for further details but if I can help anymore please ask and I'll be happy to be of assistance.