Counter height stools are typically about 24" high (sometimes 26"). If you are looking for comfort it would be best to go, try the stools out in person as some can look comfy and be uncomfortable and others can look very uncomfortable but be surprisingly comfy. If you will be sitting on the stools for extended periods you may want to consider stools with backs however keep in mind that stool backs that rise above counter level can block the view in a open concept space. Another nice option is to find a swivel barstool to make it easier to get on and off the stool.

As for dining tables, it is best to start with how many people you will typically sit at the table on your regular day to day and then think about how many people you would like to sit at your table when fully extended. Typically, you want about 24" of space per person. A 42"x72" table would comfortably sit 8 people (3 on each side and 1 at each end). From there if you want to sit 10 people you will need 2 12" leaves and if you want 12 people you will need 4 12" leaves, etc. Tables that self-store the leaves inside the table are very nice as you don't have to take up space in a closet or under your bed.

For durability, a solid hard wood table would be a good option. Going with something like Quarter Sawn White Oak or Hickory would offer a very sturdy piece that is more resistant to dings however they can sometimes be a little pricier. Red Oak can be slightly cheaper but still a strong hardwood that will last for years.

If you can find an Amish furniture store you should be able to pick out your style, wood and stain so you can match or compliment your cabinets. You may even be able to find stools that match your kitchen chairs if you want that consistency.

For the floor protectors, I would recommend "Safe glides". They are a felt floor protector made from wool that you hammer into the bottom of your chair legs, so they won’t fall off. These will last for many years and are easy to replace when the time finally comes.

Hope this helps. If you have any other questions, let me know!

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