As you head south, you'll get a good view of "liberty cap" - one of the Mammoth features.
I think my favorite drive was through the Lower Geyser Basin (also a no RV zone) on the Firehole Lake Drive. It was amazing - with several beautiful geysers.
The spring was just entrancing...
And if the lower geyser basin wasn't fascinating enough - then you get to the Midway Geyser Basin.... I think this was my favorite from a beauty standpoint.
And finally - Old Faithful (who was late, by the way).