Mix cream cheese and powder sugar until creamy. Add cool whip and vanilla. Cut angel food cake into small squares. Slice all but 3 or 4 strawberries. Gently mix sliced berries and sugar together. Let sit for 15 minutes. Cover the bottom of a trifle dish with a layer of the cake squares. Follow with a layer of the cream cheese mixture, then a layer of strawberries. Alternate, ending with the cream cheese mixture. Garnish with the reserved whole strawberries. Refrigerate for 1 hour before serving.