For some reason when you are just visiting a house, lighting doesn't seem to be a big issue - unless it's really bad. If you don't notice it then it's working well. This is different from noticing a particular fixture because it's interesting. The light should set the mood for the room or area. Dimmers should be installed in areas where you may want to reduce the harshness of the light. Besides the obvious dining room example, in your master bedroom, you probably want some recessed lights on dimmers because as you are getting ready to go to bed, you don't need them on full blast but when you are trying to match your black and navy socks then you probably want as much as light as you can get!
I searched high and low for different lights to match the different rooms in our house. I stumbled on these through various web retailers (often on clearance) as well as outlet stores and big box home stores. For example, I found some Restoration Hardware sconces for our master bathroom but did not like the
coordinating pieces but did find a
Murray Feiss overhead light which worked perfectly with the sconces and which I love!
In our kitchen, I worked really hard to find the ideal pendant lights. Although some people may think they are too large to be called pendants, I chose some large school house style lights which really fit with the era of our home, as well as the casual elegant style that I strive for
througout our home.
The most important thing is to pick what you love. Don't settle even under the time pressure of building a house or adding on. If you don't find what you are picturing, then keep looking until the right thing hits you. Be sure you leave yourself lots of time to make your decisions, but in general, you know what you're going to need even when you are only laying the foundation. So, make a list and start checking things off once you find them. This also gives you more to shop for bargains!
When I looked back at my idea book, nearly every kitchen in there had a wood stove hood with a built-in fan/ventilator. I loved the look but when I explored the price with my cabinet company, it was more than I wanted to spend. I considered giving up on the idea but ultimately decided that my husband, Jim, is hand enough so maybe he could build it. He agreed to give it a shot and our builder agreed to help install it and poke through the wall to the outside. I found a bunch of pictures of what I wanted and Jim built it out of 1/2" plywood. The angles gave him some serious headaches but he did a great job! 
