Ideally we would like the option where it is a button on the first donate page -- like this one -- you see you can just click the button then do monthly/quarterly/yearly:
Update January 26, 2018
Starting today for US customers only, you can process one-time and recurring donations on the same page using NationBuilder's integrated payment processing. You will see “Payment processing with NationBuilder” as the default option in all new US nations and in US nations that have not yet set up a payment processor. US nations that have a third-party payment processor can switch under Settings > Payment processors.
This story is developing but definitely more to come.
Response updated on October 14, 2017.
We are currently seeking US-based customers who are interested in testing a new page type that allows this. If you are interested in participating, please sign up for user testing, select "Fundraising," and note that you want to test the new page.
For now, if you create a second donation page as a subpage of your primary donation page and allow recurring donations on the second page, a button linking to that page will automatically appear at the top of the primary donation page as can be seen below: