If you're bottoming out like that, the springs are shot. Are they sagging at all? I replaced mine at around 200k for the first time (car was noticeably sagging and lower) and it made a huge difference.
I suggest changing them out with OEM all the way around, they're not too expensive. However, removing them is tough when they're shot -- using a spring compressor that compresses from the inside (ones you rent out from the auto parts stores) are almost impossible to use (and dangerous) when the springs are so close together. You'll probably need to rent a MB "plate" compressor or have a shop change 'em out.
If you like the slightly lowered look, reduce your spring pads by one bump.
Also, go with Bilstein comforts to get the original ride back, unless of course your daughter is hell on wheels in which case she might like the HD's or Sports better.
'91 300E, 208k miles