Zone 8 covers some pretty diverse geography. Where exactly are you located?

The shade tree I have planted on the west end of my house is: Tulip Poplar (Liriodendron tulipifera).

Fast-growing, tall, and deciduous (summer shade, winter sun).

Cup-shaped spring flowers that give nectar to butterflies + warblers and fall seeds to Goldfinches, Purple Finches and Pine Siskins.

Acid soil, most conditions.

Try a Paulownia. Quite fast growing...

Need to narrow things down more. How close to structures will tree be? Soil pH, Soil texture, moisture, drainage, etc.

Fast Growing : Sycamore, Cottonwood, Catalpa (but these trees can be undesireable in a yard)

Fat Growing and Quality Tree : Loblolly Pine, Willow Oak, Shumard Oak

Shantung maple, Montezuma cypress, Mexican Sycamore, Mexican White oak, Lacebark Elm, White Ash...

I wouldn't consider Loblolly Pine such quality tree after seeing many fallen pines in Houston when Hurricane Ike came through. At least not within 150 miles from the coast...

You might look at Catalpa.

I'm planning a new shade tree myself as a lawn tree so I need grass to grow under it. Other considerations for me that you might consider too:
growth rate
Stregth - too brittle a tree will be a mess
leaf size (how much mess do I want to deal with? - smaller leaves can practically take care of themselves)
shape and final height
then, any special things like nice fall color or flowers....

based on these things in my place I'm considering an Ash, oak perhaps maple if I can find one that lets grass grow. Paulonia and Catalpa are both too messy.

Lex

We still need to pin down a location. Zone 8 in WA or OR is significantly different from a TX or GA zone 8 and the recommended species for one will not necessarily translate well to the other. And issues of invasiveness (i.e. the Paulownia) may apply differently as well.

FWIW, the term "shade tree" is typically used to refer to a large canopied, broadleaved deciduous tree rather than a conifer. And it would be helpful to know what other attributes the OP may be looking for, like ultimate size and fall color, etc.

Good point about Loblolly Pine next to coast. A check of a Zone map does show that Zone 8 does get close to coast in some states.
While Southern Pines may not be a typical "shade" tree, they are commonly used for that in areas where they grow. In full sun, Loblolly not only grow tall but also out. They are vigorous, fast-growing, ever-green, fire resistant, heat and drought-resistant, and have a moderate lifespan (typically to 80+ yrs). When one mentions the word "fast" and "shade", the Southern Pines easily fit the bill.
That said I wouldn't plant one closer than 30' to the house and maybe not at all in Z9 or other places which I considered hurricane country.