I don't quite understand your question...you can apply for a travel tour (or go to a travel agency for that matter) but that has nothing to do with immigration, what should matters to you is that if you are in AOS you MUST obtain an Advance Parole or Travel Document (form I-131) BEFORE leaving the US. But if the tour is within the US then there is no problem, you don't need the AP (advance parole)...only be careful that there are issues when the places are outside the continental US like Puerto Rico, Hawaii, etc.