I'm giving you my feedback from the sibling perspective, not the mom perspective (my kids thus far are 3 years apart... thinking about a larger gap before the next one or two, like you!)
I have 5 sisters. My parents had their first at age 19, then had a kid every 5 or so years after until we they had twins at age 42. I think they were good with 4 kids, then had an "oops' that turned out to be 2 more. Ha! My oldest sister is actually closer in age to our mom (19 yrs apart), then she is to her youngest baby sisters (22 years apart)!
Anyway, I am in the middle, so I have baby sisters who are 5 years and 11 years younger, and older sisters who are 5 years and 11 years older. I think the shared experience of "family" is what bonds us, not the age difference. I feel equally close to all my sisters, regardless of the age gap. I think there was a huge benefit to being 5 years apart, we always got the High School and the teenage experience to ourselves... I always looked up to my older sisters and whatever experiences they were having, never in competition or jealousy because by the time I got to a certain stage (high School, college, marriage) they were past it. Now my youngest sisters are graduating college and settling down into adult lives, one is even engaged and it feels like it has all evened out and we are all grown-ups.
The down side is, my mom spent something like 35 years straight making lunches, helping with homework, carpooling, etc until the twins finally graduated High School and went off on their own. Poor woman, now she has to help take care of mine and my two older sister's kids since we are old enough to have children of our own!
I think it's great- from a sibling perspective. I love having the range between us all and we often laugh about my oldest sister being such an 80's queen, me being a total 90's child, and the youngest being raised in the era of internet and cell phone and all that. Quite a difference! Also interesting to compare notes because my oldest sister grew up with young, barely out of high school, struggling to make ends meet parents, and the twins grew up with experienced, financially well-off parents. I'm somewhere in the middle along with my other 2 sisters.
We have a strong family bond that ties us together and we are all very close! The age difference doesn't matter. We've all had special experiences together no matter what stages of life we were in at the time. My oldest sister used to take the twins out for "tea" when they were little, now they still go- she's in her 40's, the twins are in the 20's. It's kinda their thing. If you create a close loving family dynamic, it won't matter the age difference between the kids!