I've also taken Klonopin for a long time (9 years) and find it works well for panic/anxiety and also sleep. Klonopin has a longer half-life than most or all of the other benzos, so you don't get the rollercoaster effect you mentioned with Alprazolam. It also seems to cause less habituation than some other meds... i.e., I just went up from 1 mg to 2 mg/day after 9 years, which is still only a moderate dose.

Alprazolam and Klonopin are in the same class of meds. If you didn't have significant side-effects with one, you should do okay on the other.