I have been wondering something similar myself. We have tile nearly all over the house. It is good here in AZ because it really keeps things cooler in the summer. I've been wondering about keeping the tile in the hallway, bathrooms, kitchen and laundry, but doing wood/laminate in the living, family and bedrooms. I'm good with the wood in the family and living room. It is the hallway with all the bedrooms that I have wondered about.What makes the transition and flow good? Just similar colors? Anything else?

Ask your husband if he's happy with replacing the bedroom hardwood (engineered) in 7-10 years. Ask him if he wants to change the EXISTING wood colour (full sand and refinish) in 5-7 years (well before they 'need' it). Because a poorly thought out install (as suggested in your original post) is going to cause ONE of them to 'go'. For that reason my #1 preference = same site finished wood as elsewhere. The cost difference will be a few hundred dollars (cost of materials + labour) for a small rooms like a bedrooms. My SECOND preference is SOLID hardwood in a factory finish that is CLOSE to the original floor's colour. That way you have TWO solid wood floors that CAN BE site finished in the future. If your husband INSISTS on the installation part, then push for my #2 option. Solid Red Oak in a factory finish that is close to the same colour (or natural). That way you can deal with BOTH floors at a later date. And BTW: carpets hide the WORST subfloors possible. Let hubby know he may have to do some SERIOUS work on those subfloors before throwing down a hardwood floor. Rarely are you able to rip out carpet and lay hardwood the same day. The amount of work that is needed to get carpeted subfloors up to snuff can be $2-$4/sf for labour alone (if you hired out the job). And that's when you ask hubby AGAIN how much he will like a floor he laid if it is bouncy and squeaky and has no one to call but the guy looking back at him in the mirror. Remember: it is CHEAPER to get a professional to do it right the FIRST time than it is to call the professional to fix the mess you made. But then again, flooring professionals make a TON of money dealing with DIY oopsas. If you like your professional and want to send him MORE WORK, you can always let hubby deal with this first and then call your professional SECOND. S/He might be happy for the extra work (ahem....extra money).

It is totally appropriate and often done to use two separate Oriental carpets in one room. And it sounds like they would be the right type of floor covering for a more traditional or transitional room with the type of furniture and look you want to achieve.

If the chevron was a good color I don't think that would be a bad choice. It might look busy to you because it's different than what you have now, but perfectly acceptable for stairs. I bought carpet not too long ago and it seems like tweady colors are popular - two or more different colors mixed (in a subtle way - really just different shades of the same color). You might have better luck with something like that instead of a solid. Bring home as many sample boards as they will let you take at a time and broaden your scope to include things that are different, like the chevron pattern.