Europe - Premium seats to IST??

Hi all,
This is my first post. Traveling multi destination from SFO-IST then returning ATH-SFO for an Oceania cruise in October.
Need help booking premium seats as we are both over 6' tall and over 60!
This will be my first trip to Europe.

Would love some help know where to begin.

Thanks! Kim

Hi all,
This is my first post. Traveling multi destination from SFO-IST then returning ATH-SFO for an Oceania cruise in October.
Need help booking premium seats as we are both over 6' tall and over 60!
This will be my first trip to Europe.

Would love some help know where to begin.

Thanks! Kim

Welcome to FT!
I'd suggest you need to provide some information if you want helpful advice. Your question is too open-ended.
What do you mean by "premium seats"? You want premium economy? Business class? First Class? You want to use airline miles for award travel? Pay cash?