BUT we found that tracking all those accounts is crazy hard so we invested in software for a unified inbox, multi channel sync, owner and cleaner logins with specified access, multi calendar, an app for easy messaging, plus my favorite auto messaging. 

Use the VRBO calendars to see how often units are renting.

Finally, we utilize Google Calendar.

Jared you can go to their website and look at their calendar for meeting info, time and place.

I just screenshot the calendar and text to cleaners so up to date.

I then set a calendar reminder for when they should run out and more need to be delivered.

And when we needed a break we looked at the availability calendar for one of our STRs, packed a duffel bag and enjoyed a mini vacation wherever we were open. 

I try to schedule all my showings in a 2-3 hour window (15 minute increments) on Sundays and I can't find a simple way to keep up with times, contact names, and phone numbers using the standard calendar app for iphone.

You can use channel managers like Hospitable to synchronize your calendars between sites. 

Unfortunately, the phrases 2 tax years and two calendar years have also been used by the IRS.