I just got back from a stay on the island, and I agree that there are advantages to staying in the Simpson Bay area. I spent a couple nights at Atrium, then a week at Hilton Royal Palm (with a group), followed by several solo nights at a villa on the French side.
IMO, Atrium is a great value. It's not expensive - it's a mid-range resort with a great beachfront location. The rooms and decor are dated, and the facilities are (sometimes) in need of repair. I'll likely go back for a return stay, but then again, I'm (usually) a solo traveler, and I don't need 5* accommodations. I'm more a "Hampton Inn guy," as opposed to "JW Marriott or Westin guy" (hope that analogy makes sense).
Royal Palm is the finest resort I have stayed at on the island. I was impressed with the attention to cleanliness. During the day, there are a dozen or more people working on repair and upkeep of the resort. The staff is attentive and friendly. During our stay, there were plenty of lounges available, both sunny and shaded. Also, the pool is heated (and not just by the people sitting at the swim-up bar). It ain't cheap, but you get whatcha pay for.
Regarding SBR, I went for a walk that went through the pool area. It looked very nice to me, with similar attention to the facilities that I saw at RP. I've never stayed there, so others would be more qualified to weigh in further.
.
