How many siblings do you guys have?
I have a younger sister, and that seemed to work out fine for me. She's 3.5 years younger than me, so we never really hung out that much, though it gave me someone to ride the rollercoaster with at the amusement park, and someone with whom I could talk about how weird my parents are. As we've gotten older, we do stuff with each other from time to time (she's going to a couple of concerts with my wife and I in a couple weeks), though we're different people. I never really found myself longing for another sibling (bro or sis), though it would have maybe been fun to have a sibling to play sports with and that sort of thing. I also think it was good for my parents, as I followed a very traditional path (moved out when I went to college, never permanently returned, graduated, got a job, got married, had a kid), whereas my sis has bounced between schools, acting gigs, traditional jobs, boyfriends, living at home for periods of time, so she's kept them on their toes.
My wife and I are both on the same page about (spoiler alert) having a 2nd kid, definitely in part because we'd like our son to have a sibling. I see the theoretical appeal of having more than 2 (big family holidays, backyard badminton tournaments, etc), but just practically it's not going to happen. We waited until our 30s to have kids, so that's a factor, plus the boring stuff like having enough money and space and time (which would figure itself out, but just provide more reasons to stop at 2). I have a feeling, as with most families, we'll eventually feel like it all worked out exactly like it should have for us and we wouldn't have changed a thing.