Waiting rooms are a problem for me too, I can arrived for an appointment feeling relaxed & within 5mins of being there I'm having to talk myself down. My T's office is in a big old house, all the rooms seem to have connecting doors that creak & as one of my fears is people walking through closed doors, its hardly a restful experience. I find having something to focus on e.g the pattern on the wallpaper, pictures on the wall, working out who's appointment was next or which doctor they'd see, I know every corner of that room! I also use my walkman with some relaxation music on.
It's hard to know if the anxiety is caused by the waiting (I'm quite impatient!) hyper vigilance, or just being scared of your appointment & all it will bring.
For me I know it has mostly been the latter but as time goes on it is getting easier.
Cat