I've really grown to re-appreciate Etymotics -- I originally had the ER6's which were polar (bipolar?) opposites of my Sony 51's and 71's. While people don't tend to use "fun sounding" to describe the Etymotics, I will say that my ER6i's isolate excellently (would you need that feature?) and -- with modern music that uses "maxed out" recording technology and massive amounts of bass -- sound a lot more bassy* and "fun" than I would have thought on my 2nd generation Nano. They should be quite good with the Shuffle (the 1st generation -- I can't comment on the one just coming out).
If you want the "boom car" sound, maybe the E2's would be for you, and if you want "fun" sound with an interesting look and braided cords, the UM1's might well be your ticket, based on reviews, your preferences and everyday usage.
While I love my ER6i's, I don't use them as everyday 'phones ... I keep the very "fun sounding" -- and inexpensive -- Creative EP 630's for that purpose, and they work well ... no true isolation, and some cord microphonics, but with the added advantage of being easier to put in and take out when out and about or in the office.
[Edit: *With Etymotic foamies or (especially) short Comply foamies. With flanges, for me, they're harder to get the right isolation, and then the isolation comes and goes as I move my head.
"So er6i handles mids/highs better than the e2c?"
Yes -- lots of detail.]