I planned all of my pregnancies and I also had 3 children in 3 years (ds1 was 3.5 when ds3 came along).
I was probably influenced by my own childhood experience - I was one of 3 and there was just under 2 years between each of us. We had a ball - I loved my childhood, I never felt as though I lacked attention and even now, in adulthood, I'm close to my brothers and we are always helping each other out, getting together etc.
My children, all boys, adore each other and have a whale of a time. Almost anything we choose to do suits all of them. Watching them together is priceless. The younger ones learn so much from the older ones. Ds3 is so used to being around his brothers and his friends that he is pretty confident, outgoing and his language is excellent.
We are always out and about. Having 3 close together didn't stop me getting out. I don't find it a problem.
All of them get opportunities for one to one time but they don't seem to crave it or anything.
It's labour intensive in the early years - having 2 at a time in nappies and probably 2 that are quite dependent for getting drinks, feeding etc. It's only for a short time though and you get the stage where they are all dependent and off to school, much earlier than if you spread them out. Personally, I would not like to get right past the baby stage only to have to go back to it later.
My SIL has a dd of 5.5 and a dd of 1 - the older dd might as well still be an only child at the moment as she is so different from her sister that they do nothing together (I hope this changes as they get older). DD1 was 4.5 when dd2 arrived - she was at pre-school, just going in to reception, nappies were a long distant memory, going out was dead easy - then along comes a baby. Horses for courses but that wouldn't be my choice (I know there isn't always a choice).
As all things in life, there are pros and cons to how things work out but I'm more than happy with my close together boy gang and, more importantly, they seem ecstatically happyt too. I guess I did something right!