We just had our carpet replaced with hard wood and this is what we were told as well. The joists support the flooring.

A!!!!!!!!!!!!!!!!!

Our scenario is different - we are on a slab so floor joists don't apply to our situation. We have engineered wood floors. They run like Plan A

The first answer is, if you have solid hardwood, the wood has to be run in a particular direction. The hardwood should run perpendicular across the floor joists for more strength of the floor going over it. Not doing this can cause sagging of the hardwood and board separation.

If you are using engineered hardwood, you have the following choices below.

The second answer is personal preference; however below are some helpful guidelines to keep in mind. Often, it depends on what look you are trying to achieve.

The easiest way to make a decision is to look at the areas receiving hardwood and if there is a narrow hallway involved, then run the hardwood the long length of the hallway.

If you have hardwood in one large size room only, the direction is truly personal preference. The room will appear longer if the wood is run from one end of the room to the other.

If hardwood is in more than one room, but the rooms are open to each other, running the hardwood from the long end to the other end rather than from the front of the room to the back of the room will make the 2 areas seem larger.

Otherwise, the hallway will look chopped up.

Hardwood can also be installed diagonally or with a pattern such as a herringbone.

We were told that the length of the flooring should cross the floor joists. I didn't do that because one room was so long and narrow. I haven't had problems with my flooring. We have been in the house for over 30 years.

Thanks for all the tips. I can't wait to get started!!

plan A ... that is the way they are in my house

I have hardwood floors that extend from my dinette, through the kitchen and into the dining room. It is a loooong area. However I do have throw rugs to break it up. It looks GREAT! I think that plan A is the best way to go.
If you have animals, I do know that Pergo can only be refinished once (at least that is what I was told 20 years ago.)
I love my hardwood but I do get crud in the cracks....just part of life. WE put in natural oak and it has held up nicely but we were supposed to refinished every 5 years....oops, still waiting to do that.

Don't know about the other rooms, but when we had pergo installed in our new house, the guy put the boards in crosswise in the hall. There was a lot of waste. We had to buy extra, even though we had figured 10% more to begin with. Not happy! Plan A definitely.

Plan A is more economical--Plan B will give you a lot of waste after cuts (esp. in the hallway)
I'd go with plan A if at all possible.