Can you just share a gmail calendar with her and then enable that calender on her phone?
Yeah, the stock Calendar will do this, as well as any 3rd party calendar apps that use Google Calendar as their data source. You and your wife just need to be using Google Calendar, and share your calendars with each other.
As far as specific calendar apps, Touch Calendar is my favorite. It gives you a full month view (6+ weeks actually), while still displaying the time and appointment description (a good # of characters, so you can actually tell what it is). Which is something that the stock calendar and other 3rd party apps simply do not do (or don't do well).
The free version of Touch Calendar works great as a stand-alone app. But if you want put the calendar on your homescreen as a widget (which I like to do), this requires the paid app. But I found it worth the couple bucks to buy the paid app.