my wife drives to Uptown in Dallas - on north side of Downtown Dallas everyday.
If you leave between 7:15 a.m. and 8:00 a.m. expect a 45 minute commute. It takes between 10 minutes and 20 minutes to get out of Southlake to the north entrance of DFW Airport on S.H. 114
The Southlake to FW commute also has its challenges. First of all if you go SH 114 to SH 121, to SH 183, to downtown, you still have the issue of getting out of Southlake to SH 121. Then where SH 121 and SH 183 merge you usually have slow traffic. If you go SH 114 West to SH 170 and then I-35W, you have a lot of stop lights until you get to I-35W. Also I-35W both north and south are pretty bad in the morning and afternoon.
If you can live Southlake prior to 7:00 a.m., it drops off usually 15 minutes in commuting time.