S.S.
I nanny'd three boys from the birth of the oldest until the youngest's 5th birthday - at that time, they were 5, 6, and 7 (one month from 8).
Once there is more than one - do you ever really feel like you get to spend enough time with them? You're always stretched for time between the play time and the work load that increases with each child.
Same thing with being left out - yeah, generally if you're spending one on one with one, then two are feeling left out. Games between all 3 - especially the same gender - are helpful with this, and it passes with age. The young one is going to demand more time until they're 2 or so, but then they integrate.
As for college - my parenting experience is 3 full time kids and a step, currently 2, 5, 11, and 13. There is a commmunity college close to here where tuition currently runs about a grand a semester, not including grants and scholarships or loans. My husband and I have set as our goal having enough put aside to pay for 3 years at that CC per kid - at 3 grand a year right now, including tuition and books - it is something that we can pay at the time, if our saving falls short. Our children can then save the rest through working in High school and college, or by getting grants, scholarships, and student loans. If they want to go to a bigger school, they will have to get there through grades and hard work - not guilt trips.
I worked my way through school - my parents paid for nothing. I knew going in that if I lost my scholarship, I'd be careering it without an education - and I did not drink or party in college. That was a direct contradiction to the majority of my dorm mates, and sometimes I felt left out - but it is the educational experience I want for my kids. My husband partied through his freshman year on his parent's dollar. He still doesn't have a college degree.