There are several things that must be considered. I like to use the concept of MOST amount of flooring that follows the general rule. If you have a single room (lets say 10' x 10' = 100sf) and then the REST of the space is much, much larger (say 600sf), you would want to try to keep the MAJORITY of the flooring (600sf) sticking to the rule of "longest length = long run of the room". The other question with hardwood becomes wooden subfloors. Sigh. Wooden subfloors over joists change the equation. Hardwood floors must be run perpendicular to the joists - no matter how big/small the rooms are. So...without knowing your set-up, without knowing your subfloor, without knowing the direction of sunlight, without knowing very much of anything about your situation...the majority of the home should follow the rule of thumb. Unless other factors contribute to changing this. Which I can't tell because there isn't enough information. And just for fun...diagonal is always an option = 15% waste and a more expensive labour bill.

Excellent. You MUST run the wood floor perpendicular to the JOISTS. You have NO CHOICE. Perpendicular simply means the wood plank will run across the joist. And now you have to have someone assess the DEFLECTION RATING of the wood/joist system and it's ability to accept tile. Tile deflection ratings are VERY specific. If your subfloor is too thin or the joists too far apart then tile installs become complicated. You need a STIFF subfloor to accept tile. Tile is SUPER heavy and it does NOT like "movement" from a flimsy construction subfloor. That being said and we ASSUME you have a STIFF enough subfloor, it is no big deal to throw down tile. The wood install can be altered IF you add MORE thickness to the subfloor. If you add another 3/4" of plywood to what is already there, you can go in any direction you choose. That's expensive but it is how we get around the "joist" direction problem. The *other way around the joist direction problem is a DIAGONAL installation of the wood. That gets very expensive for two reasons: You need MUCH MORE wood floor waste (15% - 25% waste for diagonal install; compare that to 5% waste for a traditional install) 2. Labor costs are MUCH more to lay diagonally. There are a tremendous amount of cuts which means the installer could need DOUBLE the time. And time is money. Some of these guys charge $50/hour. If you DOUBLE the TIME you DOUBLE the labor costs. Personally I believe laying another layer of plywood is a better/cheaper/faster option if you MUST change the direction of the wood. Again...the traditional/required install is perpendicular to the joists. Everything else becomes a personal choice...with personal financing required.

Thanks for the replies. In the meantime I've been googling, as I probably should have done before posting this. I hadn't thought about the direction of floor joists, and I'd go with the more structurally sound direction. I tend to agree that Room 3 should go in the same direction as the hall leading into it. I'm less sure about the other rooms. 1 is my office and 2 is a 10x10 guest room dominated by a queen-sized bed. Writersblock, the flooring in the hall changed direction because I asked them to do it that way. I like it and thought it would be better than a run of short boards running crosswise.

We mostly have slabs here so joists aren’t a consideration. My instinct is to run left to right in the Pic, so you’re gping parallel to the longest wall in each room. The entry then doesn’t flow the rules, but if especially If you’re going to have a rug there, it won’t really matter too much. Then I was thinking about yoir layout and realized my sister has a similar plan, with open plan Kitchen/family room at the back of the house and had run the flooring side to side as well. And Im finding image after image that does the same.