I thought the traditional Christian vows were a mix of I do and I will, depending on the question.

erinja:I thought the traditional Christian vows were a mix of I do and I will, depending on the question.

There are two ways of making the traditional English marriage vow. In one, the couple simply recite the vow in turn ("I, N, take you, N, for my lawful wife/husband ...). In the other, the celebrant (the person officiating) recites the vow as a question: "N, do you take N for your lawful wife/husband ...?" The natural response to "Do you?" is "I do" but no doubt some prefer "Will you"/"I will".

N, do you take N for your lawful wife/husband ...?
N, ĉu vi prenas N kiel vian laŭleĝan edz(in)on ...?

I do.
Mi tiel prenas ŝin/lin

Alternatively,

N, will you take N for your laŭful wife/husband ...?
N, ĉu vi volas preni N kiel vian laŭleĝan edz(in)on ...?

I will.
Mi tiel volas.

Mustelvulpo:Does anyone know if weddings are commonly enough performed in Esperanto for any traditional vows to exist? (Ĉu vi volas...? Ĉu vi prenos...?)

They're a rarity, of course, and I doubt there are anything approaching official guidelines, but when a couple got married here in the UK, the newspaper headline read "Mi volas" to reference the bride's response to the official where she would have said "I will" or, as Terry pointed out, "I do" in English.