I dunno, with a lot of these modern motors I prefer the look of the estate to the saloon (3 & 5 series included). But maybe I'm too old now or something (hope not at 37). Older motors, yes, the saloon looks better. But not so much nowadays. Like you say though, it's the practical aspect of the estate that is the biggest pull though.
Yeah, take her along. Much better if you can look at them side by side (estate and saloon). And also if you can see the different sizes (so 3 series and 5 series for example).
What we found was that the pram had to go into the boot width way in the 3 series, but could go length ways in the 5 series. The difference here is that width way it takes up most of the boot, and length way it only takes up half the boot. So if you are right on the ball and already have your pram (or could borrow one similar to what your getting), you should really take it with you when car shopping, because how easy it fits in the boot, and how much room it takes once in, are the biggest factors at this stage (or it was for us). Obviously prams are all different sizes, and fold down in different ways, so taking a random one might not be as useful as taking one the same or very similar to the one you might end up with.
It may also be worth having a look at the likes of the Ford S-Max or VW Touran too. They are obviously smaller than my Alhambra (or Ford Galaxy), but being 7 seats means they will have bigger boots (with the seats down), but are more "car-like" in appearance and drive. Of course, there is no getting away from looking more like estates, but they might be big enough, certainly with only 1 child.
A Euro NCAP 5* rating on a supermini is not the same as a 5* rating on a large saloon... We have kids, and although you can manage with a smaller car (especially with just one of them!), the more room the better really. You'll be glad in the long run and it opens up a lot more choice. 
