All of those hydrangeas are normally under-story plants in the wild. Paniculatas are the most sun tolerant of the hydrangeas. Arborescens and macrophyllas will perform best in afternoon/evening shade in most locations. A handful of hours of sun in the morning sounds good for any of them, as most of your hot temps are usually in the 80s and very few 90s. But consider this for times when temps get hot in June-August:

Hydrangeas get heat stress when temps start to regularly exceed 85F or thereabouts. So on those rare times in June-July that you get to the 90s, be aware that the leaves may wilt. If the soil is moist enough though, they will perk up on their own at night. In my much warmer location, I try to give them shade by 11am to prevent scorching of the leaves during the summer.

Oakleaf hydrangea leaves may burn with too much afternoon sun but they are the most drought tolerant and they produce excellent fall foliage, provided they get some sun in the Fall. They cannot stand being in soil that remains wet for too long of a time though...

In the PNW, you can grow any hydrangeas other than macs or serratas or asperas with that exposure.

Thank you!

I would suggest Annabelle and Hydrangea Serrata Preziosa in the sunny location. My Preziosa is in full sun for most of the day, 10am to 8pm in the summer. Hydrangea Klaus Superba blooms like crazy in full shade! Give it a couple of hours of sun and it will perform beautifully for you. Klaus has lovely light to medium blue - green large mop head blossoms and dries easily for wreaths or bouquets. Email me if you have questions. I am located in Shoreline - just north of Seattle.