I've only used it once, for my honeymoon MIA-CUR with a stay at the Marriott there. It was cheaper via AAvacations than any other site, and I got a boatload of bonus miles. No complaints. Shortly afterward, I signed up for the SPG Amex so I haven't really had reason to book a flight/hotel combo since then (any non-SPG stays were combined with all-partner awards that obviously wouldn't work through AAvacations).