Amy and I have been sharing calendars through Google Calendar for a few years. We both have BusySync, and we have 4 family calendars, as well as one for our co-op (which I manage -- mostly just trash & recycling responsibilities), and some public calendar subscriptions.

This had gotten increasingly complicated over time, and Amy was aggravated that her iPhone & Google were often out of date because BusySync cannot sync when her MacBook is asleep (most of the time).

I came to grips with my anger at .Mac sync, which ate my data several times. Some of my problems were Palm-specific, and MobileMe has evolved sync somewhat since I gave up in 2007. I got a .Mac Family Pack (discounted), and set up our Macs & iPhones. Then I realized that iPhone OS 3 and iCal 4 (in Snow Leopard 10.6) both do direct Google Calendar sync, and kicked myself a bit. I like being able to update Address Book at work, rather than overwriting my Address Book data via rsync every morning (making it lose any local changes), so I will probably keep MobileMe for that, at least until the year runs out. I don't see myself paying for the ability to update Address Book (rather than Google Contacts) at work and Find My iPhone, although FMiP is cool.

Unfortunately, iCal's Google sync doesn't push alerts from iCal to Google, which is a deal-breaker for me, so I'm sticking with BusySync. BusyCal looks good, but I don't spend enough time on calendaring that it's worth maintaining or paying for another application. Amy doesn't use alarms, but she is still running Leopard, so she'll stick with BusySync at least until she upgrades. If I didn't already own BusySync for Amy, I might try subscribing to individual calendars from Leopard.

Side note: Google Calendar offers keyboard shortcuts.