Cats and kids and a dining set  

Super Elliptical
What about the Super Elliptical table by Hein, Mattheson & Jacobsen? It comes in different sizes. When we lived in Denmark, I saw lots of these in the homes of Danish families with small kids. There were also inexpensive knockoffs of them everywhere, even in the Home Depot-like chain stores.
http://www.nest.co.uk/browse/designer/piet_hein__bruno_mathsson_and_arne...

A little teaching of manners
Neither kids nor cats have destroyed anything in my house...yes a bit of wear/tear and accidents, but a simple "NO" seems to protect my furniture rather well.

We use
We use a spray bottle with water to teach the cat he doesn't belong on the table. I'm sure it would work with children as well...

Mil-spec
"Navy" chairs will do ya.
http://www.emeco.net/location.aspx

Suggestions
You may consider a rustic, natural wood table top instead. Whatever happens, it will just get better with age.
Or you could get a used Eames contract table and stacking side shells for pretty cheap.

A simple "no" may work for some
Not all kids and homes are created equal. A smaller home with high traffic areas and active children is bound to get some wear and tear.
Olive, do you have children? I thought I remember reading a post where you said that you did not have children.

I'm so there
Cream and Chrome, have you been to my house?!?! Sadly, we had to get rid of the cat for the kid, but we are with you. Not all kids are created equal, and Kid No. 2 is a non-stop wrecking machine.
I swapped out a perfectly good wood table for a vintage one with a laminate top. Then, the swivel chairs were too much for the little guy, so we swapped out his chair for a shell chair. The shell chair is OK, but it's a bit too much like a slide.
Now, I regret the whole thing. The beautiful wood table base is not sturdy, and I fear that we will be the end of it. We already broke the matching china cabinet -- twice. (That one wasn't anyone's fault -- it was just old and the wood already was cracked, and we dared to USE it!)
Someday, we might grow out of this, but maybe my son always will be the type that is hard on things. That's very likely since his dad is.
Get things that are sturdy and easy to clean. Don't spend a bundle now and don't expect perfect. And mark off the days until the children are grown and out of the house!!!

Thank you
Some really helpful ideas... We do say the 'no' word quite a lot, and he's pretty good really.. but I've realised that there's little point in having nice floor lamps that aren't tucked behind the sofa, our glass tables are now in the garage and I tend to be most happy buying nice design, but in slightly rough condition. Sad? Silly? Maybe..
My cat just cannot cope with any new additions to the home, and my bird chair got the brunt of it! I'm just glad I bought one with a old cover so it wasn't so hard to bear...
My wife wants a drop leaf table! Do nice drop leaf tables exist? What about fold up chairs?

The Frem Rojle
dining set came with a laminate top option.. I've seen a few of them.
The seats are vinyl too..might be worth looking out for ?

A drop leaf table
sounds like trouble to me. Will your little guy leave it alone? Mine (just turned 3) would not.
Stackable chairs might be an option for you, too. I do love our shell chairs, and even though DS's a bit too much like a slide, it works. It's comfortable and easy to clean.
I had bought a '50s chrome and laminate set, which I think would have worked well, but I found the other one a few days later. I do recommend the laminate top -- that is wonderful for kids.

Not sad or silly
It's not a bad thing to accept that you have a child and accommodate for him. I struggled with this, but really, do you want to spend your time worrying about your stuff and fixing your stuff and re-arranging your stuff? Or do you want to play with your son and relax and enjoy life?
I'm really into my stuff, but I love my son and value my free time.

@Dorieg
Ah yes, that insidious, but all too common prejudice...if you don't have kids you must be defective, clueless or both. It's assumed that if you haven't procreated, that you have never lived with children, you can't possibly understand them and you must be devoid of parenting skills. I'm sick to death of hearing that!

LOL!
Olive, I think people who don't have kids are the smart ones!

I think it's more important t...
I think it's more important to mold the child to the environment around them than the other way around. If we mold the world to suit them what is that telling them? And, yes, I'm a parent.
My mother is an antique addict and never changed her lifestyle to suit myself and my siblings. She never lost anything of real worth and never had any furniture ruined because of the kids. Instead, I remember having a respect for her things.