Caulking window screens

I have 3 entry doors that I'm replacing in rooms where I'm also adding laminate wood flooring. I'm also replacing paneling with sheetrock, painting, and replacing trim work/moulding. Should I wait til after the flooring is completed for replacing the doors? I thought I had seen somewhere that it's better to have the flooring down first so that you get an accurate reading of door height. I was just wondering, because with all the painting and trim work it would seem easier to go ahead and replace the doors before I begin painting.

We need to have our front door replaced, and we're getting a new Stanley door. Home Depot came to measure and give us the estimate, and it came back $300 higher than expected -- because they recommend spending $300 to have the new brick molding (that they'll attach) "capped" in white. I believe they want to cap it in white alumnimum, as we have white aluminum siding. The question is whether this is worth it, or if it is the home equivalent of buying rust protection for your new car. I understand that capping makes the outside trim maintenance free and would not need to be painted now, but that trim is easy and inexpensive to replace, we have to paint the door anyway, and we likely will be in our house less than another 3 years. If the door/house will look bad without it, we understand, but if it is only about saving maintenance down the road, then it isn't worth it to us. Does any one have any thoughts on this? If it makes a difference to your answer, we will be going without a storm door; and while we do not have an awning, we do have an overhang that protects the area of the door itself. Thanks!