I am a fan of both - they are sun by the same company (notice the common element of their names?), and when La Hacienda opened a year or so ago, I noticed the Inn suddenly was much improved - perhaps not wanting to be shown up by their colleagues across the sidewalk.
The two represent food from different parts of the country. If I'm remembering properly, the Inn is more northern, and La Hacienda is more southern. This may be a subtlety that most guests won't notice, but maybe the thing to do is simply look at the menus and see if anything catches your fancy.
Ultimately, the thing that may make the biggest difference for you is simply that at the Inn, the tables are very close together and some folks find it uncomfortable. This is not an issue at La Hacienda.