For what it's worth, I opened a DAF at TIAAcharitable.org in early 2018 and I've been really happy with it. (I have a 401K at TIAA, but anyone can open an account at TIAAcharitable). The minimum contribution is $5,000, and the minimum grant is $50. My opening contribution to the DAF was about $21,000 of appreciated stock (so below the Vanguard minimum), and I've "recommended" grants as small as $100, also below the Vanguard minimum. The website is easy to use, and I can give anonymously, or with my name only, no address, and thus stay off mailing lists, as Catbert points out.
With the new tax laws, we plan to contribute to the DAF in years in which we itemize deductions. I just realized, when doing my 2018 taxes, another benefit of the DAF: starting in 2019 we will have a lot fewer charitable receipts to tally up (while giving away more due to the tax advantages of donating appreciated stock).