We are planning a 3 week trip from the UK sometime next year. I would love to drive from SF to the Grand Tetons and back, camping on the way. Would like to include a couple of days in SF, 4 days on north California coast and 4 days actually in the Grand Tetons. Is this a wild idea? Any good ideas out there to help us make the plans?

Not a wild idea at all, but really quite good. You'll have more than enough time since there's not a lot to see from the CA/NV state line until Wyoming (with the possible exception of a few hours in Salt Lake City) I would suggest a full week in northern California, 4-5 days in SF, and the rest of the time getting to/exploring/ getting back from Grand Tetons and Yellowstone. Leaving SF you could stop at Lake Tahoe on the way and then over to Salt Lake City for a night stay and then on to Yellowstone and Grand Tetons. We aren't campers, so can't help with that but know that winter in that part of the country is November to April and it can really get a lot of snow. I-80 was just closed last week (April) because of blizzard conditions. It's an easy drive on Interstate 80 almost the whole way. Have a great trip.

I agree. It is not a wild idea.
I know I sometimes correspond with European visitors to whom the concept of driving 650 miles in a single day is a bit strange. But once you leave California and enter Utah, the landscape becomes very, very dry. There simply is not enough water to support life except in a few places.

You are, however, making one mistake in your thinking -- in my opinion of course. You are not factoring in time for Yellowstone!! I have been in both places and will be there in just 3 weeks!! I always allot more time to Yellowstone, even though I return to places I know well. In terms of time, the two parks are very close.

Bob's right, driving to the Tetons and not visiting Yellowstone (next door) would be a shame. But with three weeks you have enough time, so get planning! (Try the route planner at mapquest.com for a start.)

You are planning a 3 week trip here..I wish I was going to UK for 3 weeks..regarding driving from SF to Grand Teton and Yellowstone in 3 weeks time..It is not a bad plan..In fact you do not need to back track..If you are going to Northern California for some days..after SF..you could head out thru Northern Nevada or across Oregon thru Idaho and into Grand Teton and not have to back track to I-80...Which ever way you decide to go..3 weeks should be plenty of time to do it all and not be rushed..however..as the previous poster stated..it is not unusual to see snow in the high country from October to April..