Give people ownership of a piece rather than asking them to send you suggestions, and use a plan everyone can edit directly. As long as you're the only person who can update the itinerary, you'll be the only person who does.
The default organiser becomes a bottleneck: everyone sends links and preferences, and one person manually transcribes them into the plan. That's not a personality problem, it's a structural one — and it's fixable.
"Can you look into hotels?" produces nothing. "You're booking the accommodation, budget's $X, deadline's Friday" produces a hotel.
Set up the trip, share the link, hand out the roles — and let people do them differently to how you would. With bothways, everyone edits the same plan directly, so the itinerary fills in without passing through you.