As of a couple of weeks ago, we have stayed at all Marriott beach front resorts on Hilton Head (why bother with the others

. They each have their own personality and pros and cons. Here's my opinion of each . . . .
Monarch . . . . one of our favorites . . . actually my favorite going as a couple. It is small intimate and closest to the beach. As stated above by others it is with in the Sea Pines gated community. Being in Sea Pines gives you access to great bike paths under the Spanish moss drenched trees. Meandering though the neighborhoods and lagoons is interesting. The Forest Preserve is also in this area . . . basically an area with a large lake and trails where you will see various wide life . . . alligators, birds, deer and etc. Harbour town is also within this gate. This is an area with a lot of rentals so you will have a lots of vacationers. The units are updated and cozy. The cozy aspect is one reason I might not pick this resort for a family of 5. The units are the smallest of all Marriott's I have stayed in. If memory serves me correct . . . the second bedroom has two twin beds . . . so someone is sleeping on the floor or on the sofa bed. Monarch also seems to have less daily activities and amenities on the property . . . if that is important. IF you are not staying with in Sea Pine, you can gain access by paying $5 each time you enter. Most of the other gated communities on the island are restricted to owners and their gues only . . . you will not be able to get in . . . we tried
Grande Ocean . . . . great resort . . . but large! Many buildings and units. The actual units are probably the most spacious of all Marriott's I have stay at and thus gives you more elbow room when traveling with more people. Lots of activities and the pools are very nice too. IT is also very close to the beach and there is a good chance you will be able to see the ocean from your villa. There is an indoor pool but iit s not as nice as the indoor pools of Barony and Surfwatch.
Surfwatch . . . I expected this to be my favorite resort on Hilton Head. While it is first rate as far as the unit and the grounds . . was not impressed with the sprawl and the distance between our unit, the pools, market, exercise room and etc. We stayed in a three bedroom, three bath unit and there was tons of space. Each guest bedroom had two beds (gueens I think). Especially disappointing was the distance to the beach. While I knew this when I made the reservation I though it might actually be an interesting plus. There is a long board walk over the marsh area. If there had been more birds and other wild life the walk would have been interesting . . .the first couple of times. As it was . . .getting to the beach was a chore. The distance from our unit to the start of the board walk was longer then most of the other beach front units distance from unit to beach. I have been told they will drive you in a golf cart if you ask, but that seems like you are inconveniencing someone. My 82 year old Father never made it to the ocean on our most recent trip as he did not want to burden anyone. We always rent bike on Hilton Head. Surfwatch had the worst bikes I have ever rented . . anywhere . . . .rusted and really beat up and making terrible grinding noises when in operation. The attendant was not at the shop during posted hours. He had to be hunted down as he had several job titles. On the plus as I stated before . . . the grounds are pretty. The indoor pool is the best of all Marriott indoors pool I have seen. We thought that if the resort was really crowed during the summer months, the out door pools might be a little crowed as there is only one out door pool near the units. The second outdoor pool is at the end of the boardwalk by the beach. I would say this resort is best for those who like more seclusion and will only be going to the beach a couple of times. It is the newest of all the Hilton Head Marriott's and a pretty resort.
Barony Beach . . . huuummm . . . . I liked this resort. I did not expect to like it . . .not sure why. The units were nice and spacious. Unless you have ocean front . . .most units will not see the ocean as there are lots of trees in the way. It is very easy to get to the beach. Being on "the heel" of the foot shaped island was an unexpected good location. You are close to the "local's amenities" . . . restaurants (Franky Bones is delicious), grocery stores Harris Teeters- my favorite, Publixs, Bi-Low and regular stores like Walmart, drugs stores, the post office and lots more. It is also the easiest stay for getting on and off the island (with no tolls) if outlet shopping or site-seeing in Savannah, etc is your thing. There is a quaint area called "Main Street" a short drive away . . . looks like a "Main Street" with little shops. At the resort, there are nice amenities including an indoor pool. If you are into spas . . .(who isn't?) and can afford the fees . . .the big catch . . there is an on site spa for massage and other wonderful indulges . . . can't give a first hand report but I would say it would be hard to have a bad massage. This resort is close to the best shelling on the island. While you can find shells near the resort . . . a short beach bike ride will take you to where the "real gold" of shelling lies . . . I won't give up the secret but with patience, good eyes and perfect timing (just gave you all good clues . . . think tides) you should have no problems finding large (6 to 8 inch long) conch shells. To me this resort is good for those who like to "play" on the beach as opposed to just sitting (which you can do). The resort outdoor amenities are not as spectacular as say Grande Ocean (it is smaller in size) but they are nice. There is one oddity to this resort but I am not sure if it is a negative or just an oddity. The resort is located next to the Westin. Most of Barony is on one side of the Westin. There are one or two building however, that are on the other side of the Westin. Since I did not really investigate these buildings I can not give an opinion. I think there is a private pool for these building but I did not verify. The bike rental is in this area. The bikes here (unlike Surfwatch) are well cared for and the attendant makes sure they are functioning properly and are adjusted to your height before you take off.
Bottoms line . . . with young children . . . I would pick Grande Ocean or Barony. As a couple not wanting to be in the thick of the crowds, I would pick Monarch or Barony. As someone who just want to get away from it all and be surrounded by a peaceful, nice setting then maybe it would be Surfwatch (forgot to mention Surfwatch has fishing ponds. You can rent poles to go catch and release fishing in their pond. Surfwatch is a good take a book and veg out resort.
Now that I have given my 2 cents I am sure others will have differing 2 cents. Bottom, "bottom line" . . . if you are on Hilton Head, you can't go wrong . . .enjoy.