All the same. Purchase all the wood you need for the entire project, then work room by room. You will not reject doing all one flooring.

Visit a variety of flooring stores to look for a deal. It's amazing how much the pricing for similar flooring can vary from store to store. Last year we found a close out deal on the cork flooring we wanted to buy for our sons' bedrooms. Since we had visited many flooring stores before and had looked online we knew it was an amazing deal. The kicker is that we had to buy way more than we needed. It was still cheaper than any other option we had seen. We even had enough left for a future project.

We couldn't afford to install it right away so we stored it behind a sofa for several months while we saved money for installation. We didn't have the time to do it ourselves plus the rooms have so many irregular and tricky cuts we didn't trust ourselves to do it well.

Shop around and buy it all at once. Some flooring places have 0% for a certain time period so you can pay for it in installments. If you have a safe place to store it you can pay to do the house in stages to save money. Don't forget to buy extra though for overage and in case the floors are damaged in the future.

I don't recommend hardwood in the kitchen or any other wet room though. The previous owner of our former home had a fridge water leak in the kitchen and it damaged the hardwood in that area beyond repair. A similar thing happened to my best friend while her family was on vacation. The water line on her ice maker developed a slow leak while they were gone and destroyed the trim and hardwood floors in her kitchen. The contractor they hired to fix the problem claims that if they had tile floors in the kitchen only the trim would have needed to be replaced which would have saved them thousands of dollars.

Thanks for your time and input. We don't plan on hardwoods in the kitchen, so that part helps. We have a lot of oak throughout the house ie. cabinets (custom)' trim and doors. Some of this may be getting a paint job though;-)