Metroflex the Castle is one of my favorite gyms in the country. Large. Lots of equipment. Friendly owner. Gritty.
If you've never seen the original metroflex in Arlington, it's worth the trip. Nostalgia galore.
There's a tiny garage style gym off of 377 called Quads that's got all the "hard-core" basics.
Fox Fitness on the west side has some of the newer Arsenal stuff.
Absolute Recomp is well equipped. But it's crowded, full of kids and tripods.
There's a powerlifting room in the back of Strouds in Euless.
The 24 Hour Fitness off western center has dumbells up to 150 lbs. Never seen that at any other 24.