Hi! Ok...yes you have some great things going on also some tricky things.

First off the knobs and back plates, the back plates should come off with a tiny bit of coaxing with a flat head screwdriver or putty knife. Many times they get stuck on with kitchen fumes and grease. Sometimes the contractor puts a tiny dab of glue to hold them so they don't spin.

One thing that you can do is take down the upper cabinets between the kitchen and dining area. That cabinet can actually be re-purposed into a bench - all you need is some foam and material. Doing that would allow you to reduce the chairs to two and move the table back further to give you a less crowded feel. You would still be able to use the cabinet for storage. It would be preferable to get a rectangular table and lower backed chairs.

Blinds or window treatments will help brighten and tie the two odd shaped windows together.

Counter-tops come in many types from granite to concrete to Marmoleum to laminate. Each has different pricetags and different care needs. Backslashes need to be coordinated with the counter of course and I strongly suggest you look for what you want as a backsplash before selecting the counter. There is a good reason for this - many times we choose a busier countertop and then are stuck with using a bland backsplash. It is FAR less expensive to change the backsplash down the line then the countertop.

Back to your knobs and pulls. The style of your cabinets is older and certainly new handles and pulls will help. You can't go modern but a heavier oil rubbed bronze would work nicely. Lastly you may want to consider painting the cabinets if they are showing signs of wear.