In that case, I'd look into a floor mounted rogue or titan power rack/cage. I haven't used them, but if limited on space the folding ones look cool. I have a Rogue Monster Lite RML-3 and it's been worth every penny. Of course this would assume you want to get a barbell and weights instead of just dumbbells.
For bars, Rogue has boneyard bars that are a little cheaper. For plates, I'd start with something like the 160 pound bumper plate set from Rogue - it will allow you to do stuff off the ground like deadlifts and power cleans at weights under 135 if your kids are younger. But then they obviously work as any normal plates would too.
The floor mounted racks will support attachments like dip stations, will have a pull up bar, some can support a pulley for cable work. They're also great from a safety perspective because they usually have or support spotter arms or safety bars.
The bench, I'd look at Rogue, Titan, all the brands mentioned here.
Only thing throwing me off is leg extensions - no personal experience in that with a home gym but I've debated using a tibialis bar to do them off the end of a bench.
Hope that helps!
