Personally, and I speak for myself, from experience, wood in the kitchen looks nice. But the problems that come with it in there may make you think a bit more about doing it (from my perspective.)
When the floor gets wet, the finish on the floor doesn't like water. It can 'stain' the finish. Also, the water MAY run out EVERY joint and under the floor DEPENDING on the type of install (glue or nail). The kitchen is a high-traffic room, as is a family room, as is the living room (if you don't have a family room.) This means that you're gonna have wear mostly where you walk, and it will show rather quickly. You could throw area rugs and runners down in the living room and/or the family room to kinda preserve the new wood look but in the kitchen, you may not like the look. Don't mis-understand me - refinishing a hardwood floor isn't a real big deal. It's just that you may end up doing it sooner than you like. In my home, we have hardwood in the foyer, living room, dining room, and throughout the 2nd floor; not in the kitchen, family room, 1st floor bathroom, or basement. The latter list of rooms is were the vast majority of traffic is. ANd in those rooms we have carpet and vinyl (and concrete in the basement which is NOT finished.)
You need to be careful about engineered flooring. Across manufacturers, they are made differently. Some have 3 layers, some have 4. Some have 1/8" hardwood on top, some have 3/8" on top. Some quality hardwood for the 'under layers', some use soft wood. Some use 'junk' for underlayers too. So, I'd look at a few other brands so you know what's out there. Be sure to talk to the Retailer about the construction of the flooring you're looking at, and tell him/her about what 'other' types of construction you've seen. In other words, why should you buy 1 over the other. (The softer under layers, or junk under layers, when they get wet, may NOT return to their 'normal state'. BE sure to read the warranty info and installation info BEFORE you buy -in the store- to see if the flooring is rated for high-moisture rooms, kitchens, basements, etc., etc., wherever it is you intend to install it.)
Yes, depending on what you buy, you need to consider thickness and what it will do to 'transitions' into other rooms. Will you have to rip out more flooring? Will you have to cut doors? Will you no longer be able to get your foot to the cabinet 'toe kick'? Are there transition thresholds available for high-to-low and low-to-high transition into other rooms? And so on ...
As for installing the flooring yourself, in short, it's not that difficult. The hardest part is getting started. Depending on the room, its layout, and its relative position to other rooms, starting on wall A may NOT be the correct wall to line up on. You have to know why a pro starts on one wall vs. another. Also, I suggest you nail or staple. This way, you can replace boards easily. (Be sure to read the Installation Paperwork to be SURE you can replace a board. If it's not in there, ask about it to see if it can be done.) With a glue-down floor, basically forget about replacing a board. And while you're reading the Installation Instructions, take note of the 'tools' that you need to install a staple or nailed floor. Then go out and price what it would cost to rent them (if you can find them.) Then price out what it would cost to BUY them. After that, see if it's economical to rent or buy the tools. Remember, if you're doing this job on a Saturday or even Sunday, and a tool breaks / stops working, is the company going to be opened to help you fix / replace the tools?
In short, I suggest vinyl sheeting in the kitchen. And if you go with hardwood in other rooms in the house, price out 3/4" solid. (It DEFINITELY sounds different from other types of wood flooring, engineered or laminated, when you walk on it. Try this out in the store.) For the cost differences, 3/4" costs more (or maybe the same or even less), than engineered flooring but it will add 'better value' to your home. (If you sell, it's nice to read that you have 3/4" solid hardwood vs. reading nothing vs. reading 'engineered flooring'. How many people know what the latter is?) And lastly, have a pro do it either way. If you mess up the finished job, you may have to have it ripped up. Plus, if you go to sell, and it just doesn't 'look right', a potential buyer may say to themselves, "This floor looks weird. If 'they' messed this DIY project up, who knows how many OTHER DIY projects they messed up. And do 'they' really care about quality work?" (I think you get the idea ...)
Well, others may totally disagree, but that's my personal $.02. My best to ya and hope this helps.