We are thinking of going to Yellowstone for a week in the summer of 2009. We would likely be there in late June, or late July, or early august.

Any thoughts on how Yellowstone weather and other aspects (mammals, birds, bugs, water ...) are different for these different times?

How far ahead does one need to book a place in the southern (?) and northern(?) portions of the park?
We would likely stay in cabins or the less expensive lodges and would not be tent camping. But rustic cabins would be fine. We stay in Curry Village when we are in Yosemite.

Thanks!

The baby bison, etc. will be smaller and thus cuter in June. More water will be running over the falls earlier in the summer rather than later.

As of last weekend (covering June 1) there was still a heck of a lot of snow on the ground in many places in YNP due to heavy and late winter snows this year. Who knows if it will be the same next year.

Book as far ahead as Xanterra will allow you (which, I think, is 11 months).

DH and I looked over the cabins at Lake Yellowstone Hotel last Friday for the first time. There were loads of 'em and they didn't appeal to us at all. But that's just us. We may have missed something that was much better.

We're planning on booking a cabin at the Snow Lodge by Old Faithful for this October - if it's not already booked up!

-doo

You can book rooms a year in advance. I would suggest you do that if you are going the peak times which would be July and August. I always feel it's better to book early and get the room choices you want and not have to settle for a location.
I have been there first week in June and the weather was cool mornings and evenings but beautiful by the afternoon. I think another advantage to June would be you might see more animals early in the day before it gets too hot.
Whenever you go it will be a wonderful experience.

June is sounding good so far. That means I better get to the more serious planning stage now. My DH is going to hate thinking about summer 09 when our summer 08 trip hasn't happened yet. Oh well.

for this year July stay at Glacier and Yellowstone we made reservations in January. It was already late to make reservation online. For each park we had to call to the different reservation agencies (listed on National Park web sites – look for Loging reservation links in both parks) for Yellowstone: www.travelyellowstone.com
With a help of travel agents we made all 2 weeks reservations inside both parks. I believe agents can view all available places and helped us to cover park in nice loops with 1-2 night stay at each hotel. During reservation you need to pay first night cost for each hotel – if you stay at one hotel, you don’t need to pay a lot at once (our case)