I need medium size trees/shrubs/plant ideas...I am so lost please help!!?

I belt a patio last fall and now I am wanting to do a few garden areas around the patio....there is a 1-3 foot lip (depending on were you stand in the outlined/planned garden) from the garden areas to the bottom of the patio....so I need plants/small trees/shurbs that are atleast that tall so I can see them when I am sitting on the patio...otherwise planting them would be usless if I have to go out into the yard to view them......I would like atleast one tree/shrub/plant to be 5-9 foot tall but no more than 10 feet...because I have a bricked in grill area that I would like a plant to come up to the hight of the grill and that is around 5-8 feet from the bottom of the garden area....I am in zone 7a (oklahoma city) does any have any ideas??