Any suggestions/opinions on a preferred shape for aromatics to point me in the right direction?
Well here's where a lot of subjectivity comes into play, both concerning your smoking
style (cadence, condition, and cut, let's say), and your smoking
implements.
Cobs and aromatics seem to be universally agreeable.
For my own smoking, which most often includes a rather steady
cadence, a relaxed (if not entirely distracted) and indoors
condition, and most often a properly-dried ribbon or shag
cut, I enjoy smallish (group 2-3), conical chamber filtered pipes--Medico Jet Streams are my beloved, as well as a few various other billiard types; the larger percentage have decidedly conical chambers. If I really want to settle in for a longer smoke, during which I concentrate more on the smoke than whatever else I may be doing (posting on PM.com, for example), I gravitate toward a couple Savinelli bent billiards--one with a balsa filter, one without, both with deep but fairly narrow (~3/4") straight-sided chambers. The flavor of the same blend in a small conical bowl as opposed to a larger straight-sided bowl are not just discernible but pronounced. Of course, as noted above, there are so many more factors that can come into play--smoking outside yields a more muted flavor that will capture mainly the highlights and sweeter notes, and sometimes push sour notes too much to the fore. Smoking Peterson's Summertime 2010 in the dead dry heat of Houston, Tejas was a different animal entirely than in the early autumn chill in my apartment. A large bowl after a steak dinner didn't satisfy at all, while a quick bowl with some gin and tonics on the roof in Bombay was soul-swelling.
In short, the only really useful answer to give you would be to experiment on your own, and not worry overmuch about ghosting as you seek the perfect combination for
your arsenal. Just be assured that when you find the right fit, it will be sublime.