What are the main attractions in Yellowstone National Park?

I am planning a trip to Yellowstone National Park this August. My family of 4 (2 kids) will have 1.5-2.5 days to spend in the park area. This depends on how much we can cover. It will go... (first day 11am-night, second day 9am-4pm). Add an additional day in there if its required.

We are planning to visit the following sites in this order:

-Drive down Beartooth highway from Red Lodge

-Mammoth Springs

-Norris Geyser Basin

-Lodging in West Yellowstone

(2nd day)

-Grand Canyon of the Yellowstone

-Old Faithful Geyser

-5 hr drive to Helena, MT

Questions: I'd like to know of some specific activities I can do in these areas. My family is mostly there for sightseeing and pictures, and maybe some easy hiking. We haven't really been to any national parks before and just want to take in the sights on a long roadtrip and some possible activities. I'd also like to know if you can recommend any other places that I would not want to miss (taking into account I have limited time, so would not want to visit minor sites). Finally, any time recommendations of how long each area takes would be great!

Thanks everyone :)