Monarch is also directly accross the street from 2 of the 3 Sea Pines Resort golf courses. Don't take the car over there.
Other note: Barony has a great gym and spa, especially for a smaller resort. Barony's beach is great and not crowded. Barony is also close to golf--right down the road--you can walk there, too.
I only toured Surfwatch (a walk down the beach from Barony) and the units were plush. Only one building was really near the beach; the others were clustered a relatively short walk away (actually a kind of scenic walk over a boardwalk thing). Grande Ocean was pretty big. The only thing I noted when I toured there was parking was tight. Seemed very nice.
Grande Ocean and Monarch are in the most popular beach area. Also, they are near Sea Pines (Monarch is actually IN Sea Pines). Eating, shopping, clubs, grocery store, etc are right in that immediate area. I noted both resorts had a resort lock (cypher lock) to/from the beach. There was nothing like this at the other end of the island (probably not enough "outsiders" to justify it).
I like the beach there, but am going to Heritage again this fall. I like golf better, and that's the best golf deal in the Marriott system by far. Talk about no facilites at the resort, however....Heritage has almost nothing at all. Tiny "gym", nice (small) pool, hot tub, lobby lounge (always seemed closed), etc.. They share stuff with the other nearby Marriotts, like Monarch and ???-can't remember the other one 2 blocks away--also a smaller one but bigger than Heritage.
If I win Powerball tonight I may move to Sea Pines.