The choice for how close absolutely has to be done between you and your hubby.
My children are 16 months apart, and we don't regret it at all. Actually I love it. My son was born in june 95 and my daughter was born oct 96. Did I get tired at times, heavens yes, did I sometimes wonder if I would ever be able to be in the bathroom, the shower or anywhere by myself YES, but did I love it as well YES. Sure I got tired out at times, felt stresses, like feeling guilty for holding the baby girl when my boy wanted my attention, and vice versa , but I figured out how to "share" my lap with two "babies" because a 16 month old and a new born certainly are still babies in my eyes. While he was "only" 16 months he was still able to help me, he could get the baby powder (wow some messes there :-) ) or silly little things, like a rattle, but there were other things too, like he spent hours showing her how to crawl, so they could "race". She gave up her bottle earlier because her bother wasn't on one, and she kept wanting his cups, not her bottle. It was a little more cumbersome taking all the diapers, extra sets of clothes etc when we went places, and in cold weather or rain getting 2 kids in and out of a car...
but I always felt it wouldn't have been any different than if they were just a couple years older...
We are blessed that our children act almost as close as twins,right down to if one was offered something, like say a balloon or candy from the store, they would say can i get one for my brother/sister.
Of course at times they squabble, but they always have someone to do things with, and are close enough in age to not feel odd playing together. For us, it made things easier, I never have to hear even now, things like, why do i have to watch her(things my brother said to my parents-- he and I are 3 years apart)
I am also blessed that they are good friends. They genuinely enjoy doing things with the other, and I even hear Mom he wont play or Mom make her come outside... wonderful wonderful words...
To be honest with you, I had to really think to come up with some down sides. I guess besides the budget crunch of buying 2 different size diapers at the same time, the only other thing I can think of is that we took my son of the bottle a couple months before our daughter was born, and he wanted to revert back onto it for after she was born, he would grab her bottle, but then he would taste her bottle and give it to her, telling her ucky every time. (thank goodness he didn't like it...)
I never felt like I was driven insane by having them close together, I was and am still very thankful they aren't more than 16 months apart. Like today, they both had to watch some silly show and rushed outside so they can play basketball....
Heck, they even discuss their school work, friends, etc. with each other.
Sorry I couldn't give you much negative, I really can't think of anything I regret about having them close together.
Best of luck with your decision.
Mary D