1. He has to stay in hotels when he's in California. Or<br/><br/>He has to stay at hotels when he's in California. <br/><br/>Which is correct and native?<br/><br/>2. I'll be in the office on Tuesday, so I'll see you guys then.<br/><br/>I'll be in the office Tuesday, which means I'll see you guys then.<br/><br/>Which is correct and native? Why do some ppl use the preposition on and some don't. Which is the correct version?<br/><br/>Thanks for sharing!