The idea is good, but a subreddit with only/mostly Hive shares will be considered promotional, and won't grow / maybe get banned.

To build a big travel subreddit, you first need to post images without Hive links for several months. And even after that, you can't often post Hive link as your subscribers will see "okay, this subreddit only serves as a marketing tool for PeakD and Ecency" and will leave.

Such a big subreddit can be beneficial for Hive in other ways but... it's much work to do, and it requires cooperation between Hivers, and nobody will pay you for that.