For $8K there's plenty of fun daily drivers to choose from. Since you have a baby, a coupe isn't the greatest option; the only coupe I would suggest is an early Hyundai Genesis Coupe. The rear seat room is plentiful, but I don't know how new car seats fit back there. The seats are good, it handles really well, and the 3.8 has good power. It's a better car than the 5th gen Camaro.
A Mk V Jetta (06-10) GLI with the 2.0 turbo is the sporty Jetta of that generation, it's more refined than the Civic, and the rear seats are probably a little more spacious for a car seat. I have a MK V Jetta TDI, and it's real nice, but it's suspension is significantly softer than the base Jetta, so I'm gonna do research to modify my suspension (custom springs, etc.)
For RWD fun, an E90 BMW 3-series (07-13) may be a solid choice, but they're not known to be reliable. However, they ride and handle pretty good out of the box, so you won't have to spend a ton of money to make it handle compared to other cars. They're kinda big, but RWD cars need to be fairly large to have a good amount of rear seat leg room.
An E60 BMW 5-series (04-10) could also be a solid choice, but, reliability would be similar to the E90. I haven't driven one yet, so I'm not sure what the driving experience is like.
An Infiniti G35(03-07) would be the slightly more affordable, more reliable choice compared to the E90. They also get more horsepower, so that's another plus. I test drove a
G35x, but a RWD E90 so I can't compare apples to apples, but I would personally skip AWD with any sports sedan. Even though these are rear-wheel drive based AWD systems, the G35x understeered under power waaaaayyy too much for my preferences (too much weight up front), not to mention it adds extra maintenance and a small drop in mpg.
There's more fun daily drivers, but I'll let other people suggest some, especially the ones I'll forget about.