I would love to be able to get an inquiry by email from within ownerrez, reply to it, track the conversation, add in things such as "called person, left a voicemail" or "this person wants a bottle of wine and flowers waiting when they arrive.", automatically add people who inquire to a third party mailing list service, add information to the lead as I converse with them such as name, phone, email (if not already captured), address, preferred property, lead source, dates of stay, current not-booking excuse, lead value, and track all of this information. Then when they are ready click one button to convert it to a quote or a booking and send it off to them. If you integrate with a service such as mailchimp what would be amazingly useful would be to add them to a certain list in inquiry state, then when they book add them to a list for the just booked state along with their dates booked, name, city, and other fields, then remove them from inquiry state list, then when they've just checked out the ability to shoot off a survey email, and if the survey is positive ask them to leave reviews on yelp, tripfinder, etc. THEN put them on another mailchimp list of previous guests and remove them from the booked state list.
I don't know about others, but this system we would gladly pay $199/month for, if integrated with what you already have.