Speaking as someone with kids, nieces, nephews, etc...
DO NOT spend a lot of money at this point in your life if your goal is to have a house that looks good. Have you seen what happens to a couch when you add a 5-year-old and a cup of juice? Yeeeah. You can basically shrug and assume your house is gonna be a bit of a work in progress until the kids are old enough to not wreck the furniture, or you can be on a constant lookout for stray food, juice, markers, etc. (Personally, I think that sounds exhausting).
Or, middle ground: get stuff that camouflages kid-related damage. Ikea couches, for example (they're cheap-ish, usually available on kijiji -just inspect for bedbugs first!!, and they come with removable slipcovers. It gets too shabby? 70$ buys you a new slipcover that keeps it looking good until it falls apart. Done.) Butcher-block countertops are cheap, look good, and you can sand them down and re-oil after a kid takes a sharpie to them. Don't buy an antique dining room table. ;) If that's what you already have, cover it with an oilcloth tablecloth or something - there are some really cute designs for not horribly expensive. Etc.
Also, you can "upgrade" your furniture using kijiji or craigslist, while selling your old furniture there to at least mitigate some of the spending, if you decide that the aesthetics are important to you. There are ways to do that without spending craptons of money!