First thing you need to understand is that Bintan Resorts is a closed off section of Northern Bintan that was jointly developed by Indonesia & Singapore, so it is not “real” Indonesia. If you are going anywhere in Bintan Resorts, be prepared for Singapore prices and little or no access to anything local. Everything within Bintan Resorts is an easy 15 minutes from BBT ferry terminal. For many years the entire area was nothing more than captive resorts that are essentially monopolies set up to take advantage of one of the very few weekend getaway options from Singapore. Lagoi is a new development that is cracking the door (ever so slowly) on this monopoly.
We just stayed at the Grand Lagoi which was the Swiss Belhotel, now owned by Nirwana - this allowed us to spend the day at Nirwana Resort at no charge (a much, much nicer resort) and we spent the rest of the time in Lagoi. A shuttle between the two takes 15 mins. Grand Lagoi is a decent hotel and half the price of Nirwana - and not a captive resort so you can enjoy outside food like Warung Yeah which is probably the best food and price in all of Bintan Resorts, and Yeah Mart next door is also probably the cheapest minimart.
Lagoi has the best and biggest beach on Bintan Island, but the Lagoi area is still only 10% developed at this point, with most shops empty and only a few tourists, so that kind of kills the atmosphere. I’ve stayed at Mayang Sari before, just simple private villas, but the beach is good there.
Trikora Beach is outside Bintan Resorts, not easy to get to and facilities are lacking.