My buddy's fiance has a trail boss....she doesn't like riding in his jeep, so she usually follows us around with the trail boss. I don't know your wife, but I know my buddies fiance would be bummed to ride a blaster. She's more of a relaxed, not agressive like, rider. Like she gets pissed when I steal it and start driving it up cliffs and sh*t...haha.
If you're not into riding quads, I'd say the trail boss is cool for you because:
A) it doesn't even feel like you're riding anything...the suspension is super plush
B) The brakes are great
C) It's mad easy to ride...anyone could ride it.
That being said, the blaster is obviously way more fun. If she likes to ride agressively, then she'll ultimately be happy. If she just likes putting around at her own pace.....you might want to keep the trail boss.