Hey Debbie!
I'm attaching here a few photos of transitioning from a narrow, older floor to a wide plank pre-finished floor we offer so it is possible to transition flooring depending on the flow of the house (this kitchen is set in next to a dining room).

As far as solid versus engineered, it depends on your climate/subfloor/etc. There are so many factors to consider with hardwood. We offer a hardwood flooring quiz to find the right floor for each of these factors so it is less complicated in shopping. We ship direct in the US and samples ship to you quick so you can see the floor up against your current floor. Hope this helps! - RW

https://revelwoods.com/

There are many factors that can determine if you should go with engineered flooring or solid. You can get either in 3/4" thickness with the same wear layer, meaning the top layer of wood on the engineered flooring is the same thickness as the 1/4" layer on the solid. If the correct engineered flooring is chosen you'll never no the difference between engineered flooring and solid. If you are not quite sure if solid or engineered flooring is best for you feel free to reach out to me.

If you are on slab foundation, then you need engineered. Period.

Depending on the situation of the slab and other things, rift and quartered 2.25" oak flooring might be a better solution than that of engineered. Engineered has heat limitations and it can also dry out. This can cause dry cupping and the adhesive can loosen up from the top layer of hardwood and cause delimitation.

We had a similar situation and opted to take up the existing floor and replace. We have never regretted our choice. All our flooring is the same and site finished. (We are not on a slab.) Beautiful! Our installers were not the cheapest, but they did fabulous work. We initially did the downstairs. We agonized over what to do later upstairs: prefinished vs. site-finished. A decorator friend told me most people end up regretting their decision to cut corners, so we did the same site finished floors upstairs. It was messy, but no regrets. In Marie Kondo terms, they bring us "joy". If you can't afford to do it right save your money and wait a bit. It is expensive either way. You want to love the final product.

Debbie, how long ago was the existing maple flooring installed? We had maple (stained) flooring everywhere in our house in Toronto except the bedrooms. We wanted to install hardwood everywhere, and we were able to find the same hardwood, manufactured by Mirage - with the same stain, and the finish only slightly different - so slight that nobody ever notices. That was with a 10 year gap between initial installation and our additional work. So, you might be lucky if it's a well-known make and they haven't changed it since the original floor was laid. We were also lucky enough to find a spare plank of the original hardwood in our furnace room - the manufacturer name etc. was stamped on the back. Otherwise we wouldn't have known what it was.

As for the cost factor - in our recent experience building our home last year, the engineered hardwood was MORE expensive than the natural solid maple that we went with. (Preverco) There does seem to be some variation in the quality of engineered HW, needless to say. I would stay away from ANYTHING sold in the big box stores, btw - particularly the stores' own brands. Before we found the Mirage plank at our old house, we had decided to go with Home Depot's own brand of hardwood - it was a good colour match to what we had. But that, we discovered on opening the boxes at home, was about it. The quality was HORRIBLE - with about 25% waste due to knots (actual black holes in the wood, some as big as a quarter and an 1/4" deep - not just variations!), severely warped pieces and the finish was poorly applied on the edges. We hauled it all back to the store and ordered the Mirage from a hardwood dealer at about twice the price, but there was next to no waste and the quality overall was wonderful. My husband did the installation. The cost of the hardwood itself could vary as much as $3-$4 a foot, but the installation cost, assuming you have a contractor doing it, will remain the same. It is worth it to go with good quality hardwood with a good warranty - read reviews, talk to your local hardwood flooring stores.