We use Calendly all the time (and love it) and usually present it as 'grab a time that suits you' (or words to that effect). I think that makes it sound like please choose what you'd like, rather than please fill in this form and maybe I'll speak to you. I think that also allows you to avoid the 'or just send me some times that suit you', which I try to avoid because it just ends up in several rounds of diary tennis which is exactly what Calendly solves!