Both are very similar (same location, same type of building and across the square from each other). Grand is generally considered to be slightly better, more Grand and Florentine in decor and style. Westin is more consistent and has the usual Westin amenities. The Grand may have more differentiation between its various rooms (so the best ones are better and the worst ones are worse, compared to the Westin). I'd pick the Grand but wouldn't be disappointed with the Westin.