After removing any unwanted artefacts, I duplicate the edited layer and use the new layer to straighten the horizon and apply the appropriate lens correction filter to remove any geometric distortion.  I also make extensive use of the skew transform tool (with the image grid enabled) to manually correct perspective, fix converging verticals and ensure horizonal surfaces are level.  I prefer this approach as applying transformations at an earlier stage in Adobe Camera Raw can result in the loss of valuable sections of an image when these are cropped to a rectangle.  These losses can be minimised if you drag the anchor points used to apply the skew outside the original image area.  Within reasonable limits, higher resolution images can be stretched without a perceptible deterioration in quality.