I was agonising over booking a long, complicated trip I did last year, and a friend who works organising corporate stuff told me to shut up and go to a travel agent.
A nice fellow just rattled away at his keyboard and came up with an itinerary that was cheaper than anything I'd come up with myself. No charge - they scrape from the airlines I guess - and I got a free ballpoint. After decades of planning my own travel, I am converted.