Rocky Mountain National Park is beautiful in August, but also popular. There is a timed entry reservation system in place during peak hours (9am-2pm for much of the park, 5am-6pm for access to Bear Lake road). If you prefer to have the flexibility of driving into RMNP, you will need to go online to get a parking pass. These go FAST. To get a pass, log onto the site at 8:00 a.m. (mountain time) on the first day of the month preceding your visit (examples: for a visit on July 30, log in on June 1; for an August 4 pass, log in on July 1). Ideally, you’ll be able to snag a Timed Entry + Bear Lake Road pass which will give you the best access.
Simon and I have never experienced the tram, but it looks like it would have beautiful views! You can book tickets in advance.
Estes Park has a free shuttle service that can get you around town or into Rocky Mountain National Park (RMNP). The included website provides the info (along with other information)