It seems to me that the desire to have power windows comes down to a question of taste. Personally I wouldn't bother. It think that power windows are totally un-necessary and add complication and electrical load for no real gain in convenience. I figure there is not much difference in turning a handle vs pushing a button. If it were an option to not have them on modern cars I would leave them out as well. I think the thing that cured me was having problems with a window winder switch burning out on an 86 Volvo 360 I used to have. Of course the switch would always burn out when the window was down. Window winders can draw a lot of current which is apprently why they didn't use a relay in that circuit.

I am tall and find it easy to reach across and wind down the passenger window if I need a cross breeze.

Central locking on the other hand is something that I have installed and find to be a great upgrade. It took a bit of fiddling to get right but it makes the wagon much more family friendly - kids can climb into the car and start buckling up while I am loading goods. Before fitting central locking, I needed to climb in first and un-lock all the doors manually. Central locking was in a kit but I had to customise the lock button linkage in the rear doors to make it work OK.

Check out my Wiki for one way of getting wires into the doors in a robust and tidy manner.

http://amazoniac.wikispaces.com/front+door+limit+straps