I have taken Ativan in the past (for panic attacks) and found that it did not help me. Xanax did help, but coming off of it was a PITA! I have been taking Klonopin for the last 5 years, and I *rarely* have panic attacks. I do have some break through anxiety, but that's ok -- it helps me feel normal.
Ativan, Xanax, Klonopin, any benzo can be very difficult to come off of as they all have the risk of dependency or even addiction.
Having tried them all, I've found that Klonopin works best for me. I am on a very low dose, and it's surprising that I have not had to increase my dose over the years.
As someone who went from having severe panic attacks several times daily to someone who rarely has them, I am happy to be on my medication. I worried about dependency and addiction, but you know what? If I try to stop taking my meds, sure, I'd have withdrawals, BUT, I'd rather just take the meds and not have panic attacks. For me, it's worth it. I was deathly afraid almost every hour of every single day before my medication.
You just have to weigh the risks with the benefits.
There are other treatments, but they didn't work well enough for me to fully rely on them. Now I use them as back up

(relaxation CDs, self-talks, breathing techniques). Perhaps you could give some of those things a try.
Also, it's good to know that if one med does not work for you, there are others you can try. Some people only take their meds when they have anxiety or panic attacks, but that did not work for me. I have to have a preventative. Maybe you can talk to your doc about only taking it when you need it and taking the lowest dose possible.
Good luck... I know how horrible PD is; my heart goes out to you.
Oh! I also wanted to say this:
When I 1st took Klonopin, one dose would knock me out all day. I had the doc lower my dose to what I take now, and I rarely get any grogginess, though it does happen once in a while. Mostly, the body just gets used to it.