Our third child is only 9 months old so I don't think we've fully experienced the impact financially of having three kids as he is breastfeed and we have reused a lot of our clothing etc from the older 2.
There is 3 years between the first 2 and they are either great mates or fighting just depends on the day. There is 2 years 3 months between the next 2 and I'm not sure how well they will get along as yet. So far it seems as though the oldest and youngest are drawn together. And I know in my own family I am the second of 4 children and there is 6 years between me and my next sister and she is truely one of my dearest friends (mind you I hated her passionately until she was about 17

) . My sister who is 3 years older is not as close to me. I am also quite close with my sister who is 8 years younger and have been her whole life.
The age gaps has worked well for us though. Oldest is at school (although that doesn't actually make logistics any easier!). Second toilet trained shortly after baby arrived so really only had 2 in nappies for a very short while.
I have a great professional career so I have returned to work part time about 6 months after each baby has been born. Two in daycare is expensive but we are still in front having me work. I had intended to have a full 12 months off this time but work asked me to come back in whatever capacity I could manage so I have been doing 2 short days a week, with the help of my sister looking after the youngest. I return 3 days after Christmas.
We currently have a 3 bedroom, 2 bathroom, 1 living room house and we are starting to feel quite cramped and the house feels cluttered (which does my head in), so we are looking to sell and upgrade in the next 6-12 months, hopefully we can stay in the same area as we are currently only 1 block away from school and its great being able to walk to drop off/pick up etc.