Hearing this my first thought is large family gatherings like family reunions where several generations come together to prepare a meal.
Things I would be looking for if I were trying to organize this for my family to attend:
seating for enjoying a meal, picnic tables with some shade at a minimum
public access to restrooms on site
cooking equipment for the planned meal (appliances, large structures, counter space, potable running
water)
An play area for children to run in (open field would work, just somewhere safe to send the kids if they're underfoot or need to burn off excess
energy)
This is probably the bare bones minimum and isn't much (if at all) beyond what you'd find in most free public parks.
Value added things for this could be things like
growing ingredients on site and then having a guided tour where people harvest the ingredients for the planned meal themselves. This could be done both as part of a cooking
class and as a separate service.
Premixed herb blends for recipes (Easy to put these in small containers with the farm logo) that can be sold for home use. Even dried my home grown herbs are so much fresher and more flavorful than what is available in supermarkets. I'm sure the same would be true for what you produce on the farm.
edit: David is probably much more in line with profitability than I am. My family's kind of outing is usually something like a hike at a public park. We're not really very good at being spending customers.