Looking for your advice! We have seen very few National Parks and are planning a two week trip next September.... we are leaning towards going to Yosemite and up the cost to see Redwood NP and onto Crater Lake. Can we do that in two weeks? Any advice would be helpful! Are there train tours in Yosemite?

I will always have a soft spot for Yosemite. I absolutely loved it there, and look forward to returning.

I just returned from Yellowstone & Tetons a couple weeks ago, and they were pretty fabulous too!

But for me, personally, if you've got 2 weeks, I'd do Yosemite. Stay in Curry Village. Check out Muir Woods. I've never been to Crater Lake, so sorry, I can't help you there. And if you have time, head to San Fran and wine country.

You won't go wrong with either of your choices. Both Yosemite and Yellowstone offer plenty of opportunities for enjoyment, and going to (relatively) nearby parks would add to your experience of either one.

Yosemite - Sequoia - Redwoods

Yellowstone - Tetons - Glacier

would both be good options for two weeks, with about a day's drive between Yosemite - Redwoods and Yellowstone - Glacier.

If you want to spend the entire two weeks in one spot, Yellowstone would be preferred. There is a simpler more variety of entertainment near there. For me that's a minus (I prefer wilderness) but for others that's a plus.

Oh, and there are no trains of any kind in Yosemite.

i'd have to vote for yellowstone. more to do. the real question is redwoods vs. geysers! it's such a different landscape. I Like crater lake but you only need a day there.

very little lodging and if you don't get inside the park you have to stay pretty far out. at least that was the case a few years ago.

yellowstone has valleys, mountains abundant wildlife and those geysers which are so rare. IMO yellowstone and the tetons win hands down.

You have plenty of time to do Yosemite, the redwoods area and Crater Lake in two weeks. There are shuttle buses in the Yosemite valley, and there may also be one to go to Glacier Point; from there you can hike back down to the valley.

I've been to both -- and there is no contest between the scope, the beauty, the magnificence.
Yosemite does not compare to Yellowstone...

It's really subjective opinion between the two parks. Having been to both, I agree they are both gorgeous. (Although my personal preference is Yosemite.) I think two weeks at either park would be too long, so the real question is which surrounding area is best for a two week stay.
I think Yosemite fits that bill better, because you have such variety near there. It's a relatively easy drive to San Francisco from there, for starters. Then you have all the coastal attractions from there.
So, I'd vote for Yosemite.

Got to agree with Frankie. Yosemite has some gorgeous views. Redwood NP and Crater Lake are also gorgeous...with a lot of land in between.

Yellowstone is spectacular, right next to the Tetons and Jackson Hole. From there you can drive through the Wind River Canyon, one of the most spectacular drives in this country.

Or go East through Cody and Powell to the Bighorn National Forest. Then further east to the Black Hills in the NE corner of the state. I always wanted to see Devil's Tower.

These side trips cover about 800 miles of truly gorgeous country. And as much as I like California, they've got nothing like it...IMHO.

even if we could briefly assume that both parks were equal in attractiveness in scenery, Yosemite would always come out ahead due to it having a higher populous within a relative radius proximity.

You need to see both!!
Seriously, I LOVE our national parks. Yosemite was more "spectacular" and the scope is unreal. Yellowstone has more oddities (geysers, mudpots) and more wildlife sightings. Both are wonderful destinations!!

I've been to both and I vote for Yosemite, but only by the slimmest of margins.

Just flip a coin.

They are both incredible treasures. I believe Yellowstone is much bigger (or, at least it feels more spread out and flat) - you'd probably see more wildlife in Yellowstone and, of course, there's all the thermal activity. Continuing up in to the Tetons/Glacier would make it a truly "nature seeking" experience.

Yosemite Valley is relatively small (compared to Yellowstone!) and you'd probably do more walking around. Yosemite has more of a WOW factor and you feel like an ant against the giant granite walls of El Capitan and Half Dome. Yosemite outside of the valley (Tioga Pass, etc) is truly specacular as well, but in a different way.

As another poster said, two weeks is too long for either park (unless you do a back country trek). From Yosemite you can, as you mentioned, more easily see some other kinds of sights like Tahoe, San Francisco, Mendocino and some redwoods (do a big loop and see the ocean a bit too!). I think there's more opportunity to see some diversity around Yosemite than Yellowstone - but they're both so incredibly special that you can't go wrong.

I've been to both several times and you can't go wrong with either.

The only thing I would consider is that facilities in Yellowstone start closing in September. http://www.nps.gov/yell/cal.htm#Sep

Utahtea

Yosemite and Yellowstone are both fabulous but I give the edge to Yellowstone due to the proximity of the Tetons and the abundant wildlife. If you do Yosemite you will love it as we did.

Which will have the best weather
in September? As Utahtea said,
facilities begin closing in Sept within Yellowstone,
is that also true for Yosemite?

wanderlust,

All areas of Yosemite usually remain open through October.
http://www.nps.gov/yose/trip/when.htm

Last year Tioga Pass didn't close till November 25th! http://www.nps.gov/yose/trip/tioga.htm

The waterfalls can vary from very slow to dry by this time of the year, but there is more to Yosemite than just the waterfalls.

Utahtea