I would be happy to help you, but it is a bit difficult to offer proper information without a scaled plan to work from. In general, your idea to open up the two rooms would be a great start, but you need to be careful not to take out too much. Especially since you have vaulted ceilings, it is real easy to end up with a huge space that echoes from lack of architectural details. You also need to be mindful of upper cabinet storage and wall space for placing furniture when you are removing walls. I would be happy to consult with you even at long distance if you are not in my area. I have done this many times with clients. If you are interested, please contact me.
Micheline Laberge, ASID, LEED AP,ID+C

Agreed with removing the diagonal wall, in place have a walk-thru pantry and have 2 sets of windows on the right side for a more balanced look especially viewed from the exterior.

A simple question, do you have enough area for circulation between the new kitchen cabinets and the island? It is difficult to work when you open and close drawers and doors in narrow spaces.

thanks for the comments..Never thought about the island in that direction! I am uploading a new possible layout and design.

1.1/4 scale