A few of my longest blooming clematis which are vigorous growers--

Duchess of Albany Bright pink tulip shaped flowers
Madam Julia Correvon pin wheel shaped wine red flowers
Gravety Beauty red tulip like flowers
Purple Plena showy double rose-purple flowers

All are small flower varieties but are lovely and prolific
bloomers.

Thank you mwsgal ~ I bookmarked Clems A-Z & will checkout your suggestions ~ hopefully one of them will provide the shading I'm looking for this site. I undestand that Hummers tend to be territorial, as I've observed w/ this li'l one that practically parks herself in this Chelone Island site!

You can try clematis clematis tangutica, Summer snow (Paul Fargas ), clematis rubromarginata or clematis Betty Corning.
Tanguitca has small yellow flowers and flowers in September for 3 / 4 weeks.
It can become really big. I admit I haven't cut mine, so it's all over the place.
My Paul Fargas is quite vigorous. Mine has a 8 feet shoot. It is fighting with the much older tangutica and is doing just fine for a 2 year old :)
Clematis rubromarginata is a tricky clematis. If you have a well drained, sheltered soil it should survive. I planted mine, this year, so time will show. They have small fragrant flowers.
I haven't grown Betty Corning, but I've read it can become quite big.
I've heard huldine can become quite big too.

Good Luck.