I am planning a trip to yellowstone/grand teton NP this sept. can anyone provide suggestions, ideas, recommendations about what to see, where to stay, what to avoid, where to eat, etc. Will be coming from the west coast if anyone has traveled the roads and can offer best scenic route too.

I recommend the Old Faithful Inn in Yellowstone and the Signal Mountain Lodge in Grand Teton, but you may find that they're booked by now. There is so much to do there, I suggest that you read some old posts to get some ideas and then re-post with specific questions.

Of you do a "search" on this site you will get a lot of info
One of the BEST articles I have ever read is in a magazine called Traveler
published by National Geographic, Sept 2001You might check their web site for help=www.nationalgeographic.com
We usually stay in the town of West Yellowstone, just outside the park.
Then took day trips to other areas.
Good luck

The only URLs you need for info on Yellowstone are

www.yellowstone-natl-park.com
www.nps.gov/yell

In GT try to stay at Colter Bay Village, in the park. They're modest, clean and inexpensive cabins. The restaurant / cafeteria is first rate. The neat thing about staying in Park properties is the availability of the Ranger programs, daily/nightly seminars on the culture, geology and flora/fauna in the region. Also, rent a boat or take a ride around Jenny Lake!