According to Edmunds 2+2 NA is 3413 lbs and 2 seater NA is 3299 lbs. There are no OEM 2+2 TT here in the US so Edmunds doesn't list it's curb weight but the difference in weight is probably also at ~114 lbs.
Is the Z going to be your daily driver? If so a 2+2 NA is probably more suitable. It would have more space and should be "cheaper" to maintain... But if it's going to be the 2nd car than I said go for the 2 seater TT to maximize the fun factor.