There are many choices of trees that are less than 30 feet in height. CrapeMyrtle, (Lagerstroemia indica); Dahoon Holly, (Ilex cassine); ‘Little Gem’ Magnolia (Magnolia grandiflora) Simpson Stopper, (Myrcianthes fragrans); Wax Myrtle, (Myrica cerifera); Flatwoods Plum, (Prunus umbellata); Yaupon Holly (Ilex vomitoria) are just a few of the choices.

There are many choices in selecting the “right plant, right place” for trees in the landscape. There are shade trees, fruit trees and flowering trees. What do you want from your tree? Is your site wet, dry or sometimes both? Where are the overhead and underground wires? How much pruning will be needed? Do you want to plant exotic or native trees? Time spent answering these questions may save you the headache of transplanting or removing the tree later on.

If your goal is shade, the benefits of a new shade tree should be felt within 5 years. To accomplish that, a planting distance of 7 to 20 feet from the home is recommended. Fast-growing trees increase in height 3 or more feet per year, but most are short lived and weak wooded. It may be desirable to plant both a small, fast growing tree and a moderate or slow-growing species nearby so that the fast-growing tree can be removed once the other is providing shade benefits. If a windbreak is your goal, trees should be planted on the north and northwestern exposures (prevailing winds). If promoting cooling-efficiency is your goal, planting on the southeast exposure deflects energy-robbing winds. 

Additional Resource
http://www.pinellascounty.org/planting/pdf/2008/Small_trees_for_small_spaces.pdf