I think it's just fine to post pictures of your vacations. You aren't being rude. It's nice that you get to go on multiple vacations. I do know how you feel though. Every year like clock work I go to Florida for two weeks in June (and sometimes more) and to a secluded cabin in the Smoky Mountains for a week in the fall to hike and watch the colors change. I don't tell many people because I'm concerned at what they'll think or say.

I never put my vacation pictures up on my social media accounts but my sister does and it's always nice to see them (we don't vacation together). Best wishes.