I've been following this thread and just reread the OP's descriptions of his visits. On the first, he'd toured some of the great mountain ranges of the Canadian Rockies and said the US Rockies seemed "like plain vanilla" by comparison. Are the Canadian Rockies more grand than the US Rockies? In many ways yes, as they seem to go on and on as one drives through Banff and Jasper. However, Yellowstone NP wasn't created because of its mountains, so it's hardly fair to compare YNP to Banff and Jasper using that criteria.
On the OP's second visit, he essentially did the entire southern loop in one day. Obviously there was no time to see any of the geyser basins other than the stop for Old Faithful. He was disappointed because nature didn't cooperate with his very tight schedule (yes, these are natural phenomena, there isn't a boiler and valve system hidden in one of the buildings
๐ ). He saw "the big waterfall in the canyon", but probably didn't time to hike to any of the viewpoints in the canyon.
What I'm trying to get across is the need for time. When one is trying to see the southern loop of YNP in one day, one is too focused on maintaining a schedule rather than experiencing the park.
The OP wanted some specific suggestions. For one, stop at one or more visitors centers. Although I can appreciate scenery by just looking at it, I get much more out of it if I have an understanding of how things came to be as they are, what kind of animals are out there and what's their story, what is the history of man in the area. Plus, the rangers can direct you to things that might be of specific interest to you.
At Old Faithful, stop in the visitors center and find out what the predicted eruption times are for the various geysers in the basin. You might have to have patience, as they don't run like clockwork, but to me, the sight of water shooting out of the ground like that is pretty awe inspiring. The colors of some of the large pools like Grand Prismatic Spring display nature's use of the color palette in a remarkable way. Stinky? Yes if you get caught downwind. But breweries don't smell great either, but I like their output!
Hike down into the canyon to view the falls. This will be more similar to your view of Takkakaw Falls (from the bottom up) rather than just looking down from the rim. If you want the closest thing YNP has to a mountain hike, head to Mt. Washburn. From the top you can see much of YNP and the Tetons in the distance. You'll be able to see how Yellowstone sits in kind of an intermontane basin, surrounded by higher mountains. This is partly because the park sits in a collapsed caldera and why there aren't the great peaks such as are found in the Tetons. In mid-summer, the flowers along the trail are delightful.
Is YNP crowded? Yes at certain times, but not so much as the Yosemite Valley IMHO. If you are there multiple days, you can better plan your routes so as to avoid the worst of the crowds. And when one of the geysers goes off, I find that I'm so intent on the spectacle, the crowds seem to melt away. And if you're in the geyser basins in the morning or evening, the crowds are much less and the peace and serenity of the place are unlike the experience in the middle of the day.
In conclusion (whew!), one thing I always point out about YNP is that it was the first national park in the world for a reason. There's no place else like it on earth.
Ken & Allison
2 Camping Cats (1 diabetic)
1996 4Runner, TRD Supercharger, Edelbrock headers
2007 Fleetwood Arcadia, Honda EU2000i
4 mountain bikes, 1 canoe, 4 tents, 8 sleeping bags, 2 backpacks
(You get the idea!)