I'm with Zions, I think this is a weird discussion: you're looking for a DD (1.5 hours per day of sitting in traffic?) and want something characterful. That seems like a irrational approach to your situation. $30k buys you a lot of new 4x4 Tacoma to tow your race car and go off-roading and it'll be worth $31k in six years with 100,000 miles on it
I've tried talking my wife into an Abarth for months, we figured $12-14k would be a fun and cost effective way to add an Italian to the garage without stepping on the other car's personalities. Great sound, cheap cost to entry and quirky as hell. I wouldn't trust one if my livelihood depended on it but it sounds like you've got options in the event of a spontaneous break. Just keep that BRZ street legal a little while longer. Character in that same vein would be the Mini Coopers.
At the top of the spectrum. If you're looking for character and at Porsche's have you thought about a 911? In my opinion you get something more consistent than the Fiat, more spacious than the Cayman, and just about as quirky of a driving style as you can get. I nabbed my '07 911 for $30k+TTL with 53k miles on it. The argument "Cayman is faster around a track", while true, won't apply to you since you have the BRZ for track duty. You'll have the same engine issues (IMS) in either Cayman or 911 pre DI, same Porsche tax on parts, but less headache for DIY projects. The 911 is a complete PITA to work on, I can only imagine how much more aggravating the Cayman is. Cayman has character but I'll agree with Talus: it and the BRZ are on the same spectrum. I passed on a Cayman because 1) I already owned an S2000, 2) I don't fit comfortably & can't get inside with a helmet on, 3) it drives predictably and consistently and 4) albeit gorgeous - wasn't the shape I wanted for the same $.
If I fit, however, and needed to consolidate to one parking space I'd buy a 987.2 Cayman/S - use the saved money over the 911 to buy an extra set of wheels & rubber, ramps and jack stands and a few wrenches. Then drive it for 500k miles.
The 911 (and the terror that is driving it quick!) gets glossed over on its driving dynamics because folks don't take off the nannies and explore - maybe the higher price to entry shaped the demographics of country club drivers. It's an absurdly solid car that quickly turns the pucker factor on driving it like you would a typical sports car - which I think is a riot. It gets white knuckle on the way to speed - puts you on edge because you're driving it counter intuitively, which is different than say the S2K or BRZ (with rubber) which is predictable and confident on the journey there. Jumping between my S2k and the p-wagen on Sunday drives or at the autocross is criminally fun, they couldn't be further apart. Sounds like you'd get to experience that polarity, too. But the 911 is not nearly as input involving. The long gearing, displacement (torque) and wide rubber means you park it in third gear and focus on steering and throttle commitments.