Unfortunately, quick growing and a long lived, quality trouble free tree usually aren't found used together. You're wanting a big thick tree RIGHT NOW. Unless you're willing to spend thousands of dollars to have a 12" caliper or larger tree installed, it will still be 5-8 years or more even for a fast growing tree to develop a canopy large enough to get relief from the sun. We have a lot of Bradford Pears planted up here. They are fast growing and absolutely gorgeous until an insignificant ice storm splits them down center or breaks off major limbs leaving a grossly unbalanced disfigured tree.

I would not particularly trust the landscaper nor completely distrust him either. I suggest you get yourself to some quality nursery experts (the Ag Extension office comes to mind) and see what they recommend. The Ag Extension probably has a list of recommended trees and shrubs on their web site. At least give them a call and ask them about what is being recommended to you.

Definitely montezuma cypress. It is evergreen cousin of bald cypress. I am fond of Nanjing beauty cypress from botany shop garden online. Boy it isvery fast grower. The director of Dallas arboretum liked it enough to order more of these. Fertilize and water properly and you will see 50 ft in 10 years.

Jesse,
I follow the fast/ slow rule. I plant a tree that grows fast to provide immediate relief anad another that is slower growing. I know that normally the fast growing tree will need to come down at some time, but I still get the shade when I need it. Considering that I normally only spend 5 -10 year in a house this is a good compromise for me. You can also plant some shrubs close which will shade quickly like vitex or duranta.

Thank you all for the great suggestions!

Drummond Maple would be one to consider in Houston.

Here is a link that might be useful: Drummond Maple

Houston Chronicle had an article about top 10 fast growing trees in Houston. Check it out. I'm surprised Lacebark Elm didn't make the list since it is one of the faster growing ones where I live.

Mexican White Oak is often recommended as an alternative to Live Oak where oak wilt is. It is an evergreen oak with significantly faster grower.

Shantung maple is no slouch either but it doesn't get very large. They seem to grow fast at first then slows down and start spreading out. Nice fall color though. Think of it as tough version of Japanese Maple.

Here is a link that might be useful: Top 10 fastest growing trees

I love my Natchez crape myrtles. They grow fast, even in my part sun. They have gorgeous bark! It is a cinnamon color and peels off like a birch tree. Not much mess, but very textural.

I've never had a bit of mildew on them and I live where fungus is the first culprit on my most likely to be the problem list.

Here is a link that might be useful: Natchez Myrtle