I've always taken my babies out at night if I was going out. It's not as if we live live in a particuarly cold climate but TBH even if I was living in a cold country I'd still take my babies out at night.
Viral illnesses (including Croup) are transmitted just as easily during the daylight hours so to me a bigger issue is the health and hygiene of anyone we might be visiting.

I'm not a big fan of the idea of putting my life on hold because I'm a parent. Having children changes ones life enough without burdening oneself with too many restrictions. I never changed my diet for the sake of BF and Imran is still going strong on the boob at 14 months. I'm pretty sure that if I had placed all sorts of restrictions on my diet I would be keen to end our breastfeeding relationship by now. Of course, what works for me isn't what works for other Mums. I'm sure there are women out there who aren't at all fazed by the idea of 2 years without coffee lol.
In the same vein if I decided to stay home at night I know that I would end up feeling unhappy about it and that would impact on my relationship with my children.
That said when we eat out now we don't linger over coffee and dessert the way we used to lol. We eat and bolt (before the wait staff notice the mess our children have made :P ).
It was so much easier when they were teeny because they would sleep in thier pram while we ate.