There's a lot of levels in this pack, so many that my eyes glaze over. One that caught my attention is "Kingdom of Cydonia".

This doesn't get as much play-time as maps like Werefrog, but to me it's every bit as enjoyable - lots of rooms and halls and elevators to run through, with a nice central room with pillars and sniper posts. Good ammo and weapon replacement keep every section of the map used.