Hi Cecile,
We looked at a couple different tools, including TimeTrade, but decided on YouCanBookMe because it had the most flexibility. TimeTrade is designed to integrate with Marketo. YouCanBookMe isn't, but we have the leads fill out a demo request form on a Marketo landing page first so that we can segment the leads before we send them a YouCanBookMe link in an email from their sales person. So having the information integrated directly with Markeo wasn't as important to us.
For our CRM we use Insightly, which integrates with gmail easily (as does YouCanBookMe), so it works for us.
As for how it works, we include a link in our Marketo email to the lead (
http://centercodedemo.youcanbook.me/). When the lead clicks on the link they're taken to an interactive calendar where they can pick the best time for them based on when our sales person is available. YouCanBookMe can check against multiple calendars and automatically adjust for the lead's timezone. When the lead picks a time, it's auomatically added to the sales/trainer/etc's calendar and all the confirmations and reminders are handled automatically. It's even set up to take payments if you want to use it to book paid consultations.
We've just started using it, but it's going really well so far. Let me know if you have any other questions and I can do my best to answer them!
Emily