If you want to play it safe, take the mature spread of the tree you are considering and divide it by two. That's your distance from structure.

That would be playing it safe, but would not allow for much shade on the house or near the house.

I always tell people to put the tree as close or as far as you would like, always keeping the risk factor in mind. Obviously, the closer to the house, the more risk that it will fall on your house one day. But if you choose a variety of tree that tends to be strong, the risk diminishes.

It sounds like you are reasonable and not expecting a tree that grows 5' a year, so there should be many trees that meet your expectations for strong wood and shade potential. Someone more familiar with Oklahoma zones and weather would be able to help you out insofar as a tree variety/species goes.

Something that pops in my head is oak, but I'm not sure which varieties do well in Oklahoma.

As the sun moves further north in the sky in the summer - solastis is June 21± - the hottest part of an Oklahoma summer is beginning. On that date the sun is setting as far to the northwest as it will during the year, but also will begin to set a bit further south each day after that date. But as this happens there will be a month to two of hot afternoons left. On September 21± equinox occurs, and the sun will set due west. Still can be hot in Oklahoma on that date!
Having said all that, the most effective location for a shade tree would be west to slightly northwest from the area you need shaded most.
Hope that made sense.
hortster

Where in Oklahoma? Bald cypress and shantung maple come to mind if i wanted to plant close to the house to maximize shade. Shantung maple has strong wood and according to Kansas University, it's one of best trees for ice and wind resistant. Bald cypress don't really have large limbs that would get dropped on the roof. It grows very tall and eventually broad. They have decent growth rate 2-5 feet a year depending on soil, fertilizer and amount of water.

Avoid pecan, bradford pear and silver maples. I've seen them get split apart by storms and falling on the houses. You can see that I live in Texas where summer can get really hot for a long time so I have a bunch of trees planted around the house but it's going to take a while to get sufficient shade to make a difference. Some of my neighbors have no trees at all which I don't understand. I guess they like paying 300 dollars a month on electricity bill....

What Lou said! Got a Shantung, love it. Tough. Also for you, baldcypress if you can give it LOTS of water in OK drier summers. Eventually gets BIG. Blackjack oak and post oak were the volunteering OK trees on the family homestead near Ralston, and kept expanding, so I guess those would work for someone wanting slow but longer lived, medium height Quercus species in OK.
hortster

Check the link below.

Also, this one: http://extension.missouri.edu/publications/DisplayPub.aspx?P=G6900

Here is a link that might be useful: Landscape planting for energy savings

Prefer big oak or ash or similar trees to be 22-24' from house, maybe 20' if on corner. Can plant smaller trees around 12-15' away from house (Crepe Myrtle, Mexican Plum, etc.)

Plant on SE and SW corners as a general rule of thumb for shading. Might add a 3rd tree on west side for additional shading if lot and spacing between trees allows it.

Bur Oak and Bald Cypress usually have very extensive root systems and are unlikely to ever uproot. Have seen Eastern Red Cedar and Arizona Cypress planted within 5' of house without apparent problems. Myself, I'd never plant any medium or big tree closer than 18' and prefer 24'.

Thanks for the suggestions! We live in SW OK. We will be looking around on those trees and doing some measurements.

I own and love plenty of white ash thanks to the previous owners. Maybe avoid the native white and green ash trees in prime / dangerous spots in your yard until we see how this emerald ash borer bug plays out.