In general, I wouldn't want to pass off that level of control. Maybe if I'm really busy and an assistant knew me really well... And there are certainly sometimes heavily scheduled trips where your "handlers" pretty much just tell you where to be and when.
But, especially if it's my money on a trip I want at least some "me" time, I probably want to take at least a cursory look at flight and hotel options and lots of other details.
That's also a detail a human assistant would know about you, and would know to pass the information on to you for confirmation before they took action. I would expect a SmartAssistant to do the same.
The point is "Alexa play music" is a huge distance away from what the product should be.
But, especially if it's my money on a trip I want at least some "me" time, I probably want to take at least a cursory look at flight and hotel options and lots of other details.