I'm in the middle of setting up a wellness tourism platform and trying to decide if I should go with ability to instant book or just be the person that passes on the leads/connects users directly with the resorts. Some resorts are ok with me doing bookings, others want to deal directly, but I want a seamless, standard experience for customers and not half bookable, half unbookable. What's the best route to go?
This is not a question you should ask experts. You should be having this conversation directly with your potential customers and clients.
Before you build anything more, you should check out the book Disciplined Entrepreneurship, which outlines the steps to take to answer questions like these in the fastest, cheapest way possible, by conducting a very specific type of customer interview. You can also find a lot of information on a website called CustomerDevLabs.com.
Additionally, building a two-sided marketplace is far more challenging because you have to solve a problem for two parties at once, and most startups fail to solve an adequate problem for even one set of customers. If there is any way at all to do so, I would focus on solving the problem for one side of your market first. Rather than have half bookable, half unbookable, make a directory of resorts or providers that is focused on a narrow niche, like yoga retreats, or something similar, and make it as easy as possible for the customer to book themselves through the provider's website. Once you have created a website that is very useful to tourists and they are using the site to go 90% of the way to a booked reservation, then you can go to the resorts with customers in hand and immediately provide considerable value to them.
I have built a lot of two-sided marketplaces and solved the chicken and egg problem many times. Let me know if you want to talk through strategies for this, but first I would suggest reading at least the first nine steps in Disciplined Entrepreneurship.