Yep I concur with the others here. I have a 15 month age gap and really think that all the positives were big. Such as the lack of jealousy, being able to be close enough in age to play wonderfully together, as already mentioned here by others.
The down side was the first few months were tiring, but as the oldest was still having afternoon naps, I often managed to get both of them down to sleep at the same time, and take an afternoon nap myself too - a big advantage over having a toddler who needs your full attention all day.
I did not bother with a double buggy, my oldest only managed to start walking just as the second baby arrived. But using a sling for the baby and toddler in the buggy to start with, then baby in the buggy and toddler on a buggy board or walking.
With your being an older mum (as I was when I had my two!) it might take a little longer to concieve, (or not as in my case!!!!) so might be good to consider starting ttc earlier.
I have kept my two in sleeping together in the same room, and have no problem with them waking each other up.
I will try to think of other practicalities later and come back to you.