Offer two complete choices
Send two options with the same basic information: meeting point, activity, estimated total per person and return window. Don't compare a fully priced beach day with a vague suggestion to “go somewhere green.”
Ask people to choose only among options they could actually attend. Keep suggestions closed once the vote starts, or the decision will keep moving.
Separate interest from commitment
A reaction to a message isn't a booking. After the vote, ask for a direct confirmation by a stated deadline. Explain whether a payment is required and what the provider's cancellation terms are before collecting it.
Use confirmed numbers for transport and seating. Keep unconfirmed friends on a waiting list rather than quietly charging the others more.
Send the final version once
Write: “We're meeting at [place] at [time]. The shared cost is [amount], covering [items]. Food is [included/separate]. We leave at [time].” Fill every field before sending.
Put that same version in your outing plan. If something changes, send a replacement with the new detail highlighted in ordinary words. Don't make guests reconstruct the plan from fifty messages.
Rules, fees and opening hours change. Confirm anything that matters before you rely on it.