We started with 2 civics and two children. This worked fine except for longer car trips (think 12 hours) and camping. But if plan on just short road trips and no camping, you should be OK.
You'll find that the concept of a hatchback with fold down rear seats for storing large things like bikes is not so awesome with kids. Once you get those #&-%$ car seats in, you won't want to take them out to stash your bike except under dire conditions, lol.
Seat choice is super important with this. I have to put a bunch of work stuff in my car semi-regularly, and I actually prefer taking my Mazda3 instead of swapping for my wife's CR-V because my seat (Graco MySize) is a bout 100x easier to install/remove than her's (Recaro PerformanceRide). Both a great seats, but the Recaro is a tank, and a total pain to tighten down. Loading three Pelican cases and a cart into a compact hatchback requires a little bit more creativity, but it's still easier than dealing with the Recaro.
Also, don't bother with LATCH, it's stupid and the weight limits are including the seat, so they're way lower than just using the belt properly.
There's a FB group, I think it's called Car Seats for the Littles, where someone or other has basically tried any conceivable car/seat combination and you can get a sense of how it works before buying anything.
With regard to car choices, I would say just buy something that meets your current needs. If you're buying 4-10 years old in good condition, you won't be taking much of a hit on depreciation if you decide you need something different a couple years from now.
And because this is MMM, have you thought about whether you
really, really need two cars? Maybe as a test, try just parking your car for a week or two and only using one car.
