Choosing the host of lighting fixtures for our renovation has been the most difficult part of this project (the 2nd hardest was the paint colors!). One has to consider style, color, cost, voltage, wattage, placement, and whatever you choose needs to be in stock. There's also the question of whether you want the fixtures to be an artistic focal point or just provide ambiant light. Also, I found it daunting to be choosing fixtures before the rooms had any furnishings.
As my family happens to be in the lighting business (Hi Dad), I had some help with the exterior fixtures. Specifically, we chose specialty lighting from B-K Lighting that highlights all the features of the new screened porch. We are a low-voltage beacon in the night. No one will have trouble finding us from the water.
For the interior, I used Lighting Universe web site. I highly recommend them, they are patient, their paperwork and communications are clear and timely, and they have an amazing selection. The first group of fixtures I chose fell through because the chandelier was discontinued. Everything had to be canceled and then I started over. I ended up with the manufacturer Quoizel for all the coordinating pendants and chandelier.
When the lighting goes in, you know you are closing in on completion. We are 8 months into the project -- and almost done. Well, except for all the decorating!