I'm going to go out on a limb and say that lamps are personal. More often than not, when I'm shopping for a lamp, I'm doing so with a specific room in mind. Sometimes, though, when I find a lamp at a thrift or antique store that I absolutely have to have (and the price is right), then I'll buy it and figure out where it'll fit in.
Now, having spewed my affinity for lamps, my rule of thumb is always budget. If I find a lamp that I love and was exactly what I was looking for, but is out of my price range, then I'll pass. Patience is my thing because I know eventually I'll find one, or even design and make one, that will be perfect.
Case in point, this DIY lamp that I made from a vase!
When I was doing some inspirational shopping for a lamp or two in the dining room, I wasn't finding exactly what I had in mind. I certainly shopped thrift stores and salvage shops, and even ventured in to a few lighting design stores. Yet when I would find a lamp close to what I wanted, it was at a full retail place and the price was way too high and out of my budget.