I can tell you all you want to know about Brianna's! We just spent the week there (May 8-16) and had a great time. It's the cutest place, and after riding our bikes up and down the beach, we were even more pleased with our choice.
It is right on the beach, but realize that part of the beachfront there is also a road. It's not a freeway, mind you, but golf carts, trucks and taxis do pass by, not to mention school kids and others either walking or riding bikes. I just don't want you to have the impression that there's a private little beach at your front door. The yard is completely sand, the only garden is the two potted plants in front. There's two bikes in the shed out back and we used them extensively to ride through town, up to the store, and all throughout the island. We didn't even find it necessary to rent a golf cart.
At the end of the pier right out front at Patojo's, there's a great swimming/snorkel area. It's bouyed off, so boat traffic isn't a concern. It's fairly shallow, starting at about 4 feet and going to about 10 feet, and there's a little reef out there with a few fish. We saw squid, lobster, fish, conch and a spotted electric ray.
It's a short walk to shopping (grocery, bakery, etc), -- about 10 min -- but once you're on the front street (Barrier Reef Dr.) everything is at your fingertips.
You don't mention how old your kids are, but there are a couple of neighbor kids that my husband played football with, ages 6-8, and other kids joined in too.
I hope this answers some of your questions... email me if you have any other questions.
You'll enjoy your trip whichever location you prefer.