Yeesh, yea if you're looking for a relaxing time Costa Rica is way better. Hong Kong and the Kowloon Bay area in general is great place for shopping and night life (but don't mention shopping because if she's like my wife the debate would be over right there, and not in your favor). I'd use Costa Rica's natural beauty and beach/adventure activities (if she's into that) to hype it up. Plus it's a lot less flying time - my wife hates flying, but loves to travel
. You can take one of those nice leaisurely small boat cruises up the river and enjoy the rain-forest, chill at the beach and have pina colada or two. Unwind. Hong Kong is busy, noisy high energy and more a place to go if you're looking for an ultra-urban/party sort of trip. My .02.