Everything Birdjaguar said, plus:Do I want two more kittens?Ma'am Vickie at Kayla'a is giving away kittens. So do I want two? Zkribs love kittens.
I discussed this with my cook and her two daughters. I don't bend over well and I'm not quick, so they would be the ones taking care of the kittens.The kittens would sleep with me & their litterbox would be in my master bath. They are not needed for warmth. The consensus is for male kittens. I want two, fearing that just one would be ganged up upon by my pre-existing cats. who are now teenagers.
Irish is very pro-kittens. JJ is taking the traditional "whatever you want, sir," stance. Their mother methodically went through the problems and solutions. which I take as leaning pro kitten. My driver is leaning anti-kitten.
Advice and insight is sought. [Yes, I have 5 dogs, but they are outside dogs.]
You'll need to budget more for vet visits. Unless you want a chaotic, smelly home, neutering at 5 months - or as soon as they give off a musky smell (whichever comes first) - is crucial. It means the males will not want to wander in search of females, they will be less likely to fight, and your furniture will be safe from spraying (once they start, they don't stop even if neutered after they start). Bonus for neutering: their personalities tend to mellow. Both my male cats became gentle, furry marshmallows, and any fights that happened among them were usually remedied with honeysuckle twigs (both my male cats - Tomtat and Gussy - became very mellow as soon as they got a whiff from the twigs).
I take it you'd end up with two sets of same-sex siblings? It sounds like a good mix. You'll need to be careful in introducing them to each other. Just letting them loose in the home and letting them sort it out themselves may be painful for them (scratches, bites) and for your ears.
Your current cats may experience jealousy and a feeling of being "replaced" by the newcomers, so be prepared to lavish extra attention on them to let them know you still love them as much as you always have.
The good news is I have many coconut trees which prove to be excellent for climbing. This climbing works on their claws like scratching post. At first, I panicked when I heard my teens scratching on my couch. But after 8 months, the fabric is damaged in only two small places.
Later, he got diarrhea and befouled my top sheet. 
In the morning, I discovered my kitties like to play in their litter box and track pooh everywhere. I also learn that in my household, the traditional midnight snack for kitties is rice and shrimp. The smell of seafood makes me sick. For me, my bedroom became uninhabitable. 
, but Poseidon sits pouting on the 2nd-floor porch of the little house. 
