my go to is always a blazer. if you are doing a solid dress you could get away with a fun striped blazer or a pattern. The other option would be a cardigan but I personally am not a fan, they hang funny on me.
I agree that this dress is perfectly professional all on its own, but I think you are limited to a jacket or blazer or cardigan.
That said, you have so many options other than a "boring solid blazer".
Ann Taylor's site alone has many options:
Any of those jackets break the boring blazer mold and can add a pop of color or style to the dress. I love the dress! Take it with you to a Nordstrom or even an Ann Taylor store and ask a sales person to help you find something to go with it.
And make sure you post pics once you settle on something.