Labcorp

This location is close to my home, easy to find, they’re quick and relatively painless. I had to have about 20 tubes of blood taken awhile back, and it was blessedly simple. They used a little blood draw ‘extender’ so I wouldn’t feel the pressure in my arm of having to replace each new blood tube. I’m a notoriously light headed (read: big baby) ‘drawee’ so this helped a lot! As phebotomists go (IMO they’re probably barely a step up from the love given to ‘raging anti-​dentites’*) they do a great job. I did not need an appt for this, but I did go early in AM, so only waited about 5 – 10 minutes.
*those who hate going to the dentist, according to Kramer.

Note: This business is a lab that does blood and urine testing/​screening. There’s not really a finer grained Unilocal category besides «Medical Center». .
I’ve been having my blood drawn at this location on a quarterly basis for a couple of years now. It’s conveniently located near my home, and is easily reachable from US 75 in Allen. It’s on the second floor of a nice medical building across the street from Texas Health Presbyterian hospital. Waiting times can be a bit lengthy in the mornings, due to patients needing to do fasting testing, but they move them through quite quickly. Most of the technicians are experts at getting blood out of the proverbial turnip (e.g. me, a notoriously difficult «stick»). The waiting room is clean and quiet, with a TV running one of the health channels, but it’s not particularly large, seating maybe a maximum of 12 people.
Still, if this location is convenient to you, it’s not a bad place at all.