We may visit the Smoky Mts in August, how many days are needed to get a good feel for the park? We enjoy day hikes with scenic vistas. What are the "must see" spots there? (This will be our first park in the "east", we've been to Yosemite, Kings Canyon, Grand Canyon, Great Basin, Zion, Bryce, Arches, Canyonlands, Capitol Reef, Mesa Verde, Yellowstone, Grand Tetons, Glacier, Banff, Jasper, and Yoho.)

FWIW, we're in the trip planning stage, too. I figured 3 days would be about right for us, but it all depends on how you define "a feel for the park." I have a cousin who spent 2 weeks at Bryce. I think her idea for a feel was seeing every rock

Try to avoid the weekend due to crowds.

Add the Cataloochie Valley to your list of "must do" things in the park. Elk were reintroduced to the park a few years ago and in the evenings they come out there to feed. The area is accessible only via gravel roads, but 4WD is not necessary.

I suggest staying in Townsend. It's on the other side of Gatlinburg, closer to the park's entrance. I was just in the park for Easter. 3 days is good unless you want to head over to Cherokee, NC and mine for rubies.
You want to visit the Caverns near townsend, tubing down the river is a def must and in August. You'll need to stay cool.

The showy flowers, mountain laurel and rhododendron and flame azalea will have finished blooming by August but a few day hikes you might like to take include: From Clingman's Dome parking lot. Take the trail to left to Andrews Bald. The blacktopped trail to right goes to the observation tower. Near the top could branch off and take trail to Silers Bald. In Gatlinburg take traffic light 8, turn right and follow it to the Roaring Fork Motor Nature Trail. The Rainbow Falls trail is off this road. Go on Wed and may see the llama train carrying supplies to Mt. LeConte Lodge. Six miles past Gatlinburg take right into Greenbrier and trail to Ramsey's Cascade (left at bridge) or Porter Ck Trail (right at bridge). If you plan on visiting Laurel Falls, be there before 9am to get a parking spot. In Cades Cove park in the picnic area near the far point before you start coming back out of the picnic area and will see gate across road which lead to trail to Spence Field and Russel Fields (balds) and to Thunderhead Mt. Take the Rich Mt. Road (one-way out of park into Townsend)for view into cove and the Primitive Baptist Church far below. Pick it up directly across road from the 2nd church on the Cades Cove Loop Road. When reach the half way point of the loop road, Cable Mill and all its buildings will be on your right, go straight across onto gravel road. Goes back several miles passing a couple of old homes. Abrams Falls (can walk behind) also off the loop road is nice to visit with chance to see otter. If they ever reopen it, the Parson's Branch Road (oneway out of park) is nice as well. For great place for sunrise photos go to 2nd overlook on the Foothills Pkwy driving towards Look Rock Campground. Clingmans Dome parking lot is also good for sunrise and sunset.
The Chimney Tops is great trip as is Alum Cave Bluffs to top of LeConte. Charlie's Bunion off the Appalachian Trail starting from Newfound Gap is another great hike. They are working on the parking area at Newfound so may be difficult to park here. Will take you about 90 minutes to get to Catalooche area to see the elk (early and late best. Will have about 11 miles of gravel road to travel before you get there. Smokies is only park which doesn't charge an admission fee.

Thanks for the info. Any more comments will be greatly appreciated.

I made reservations for my daughter and cousin at LeConte Lodge on Mt. LeConte for August. It's one of the highest peaks and the only way in and out of the lodge is to hike. The shortest route takes about 5-6 hours. Weekends usually are fully booked a year in advance but you might be able to get a weeknight. Cost is $89 a person and includes dinner and breakfast. I think that's quite expensive for cabins without showers, but they have to bring supplies in by llamas.
http://www.leconte-lodge.com/about.html

Just got back from our trip to GSMNP and was somewhat disappointed. Opihi, you don't mention what part of the country you're from, but I'm from the Northeast, and felt that the park didn't really offer anything significantly different than our state parks (other than a bit more elevation, but in no way compares to the incredible scenery and diversity of the parks you mention in the West.) Another difference between the East and West is the humidity. Even though temps were only in the 70s, it was pretty uncomfortable after hiking for a while.

We stayed at Harrah's Cherokee and it was a beautiful hotel.

The Alum Cave Trail was a nice hike, as was the Smokemont Loop Trail (a moderately strenuous uphill.) There were nice views from Clingman's Dome, which is a 1/2 mile uphill on a paved path from the parking lot. I can't figure out the attraction of Cades Cove. From Cherokee it was about a 2 hour drive, then once you get there, you literally CRAWL around the loop road with stops at a variety of unimpressive cabins, etc.

Now that it's over, I think 2 days is more than sufficient. I'd skip Cades Cove, which took a good part of one day, from where we stayed.